This is Part 4 of the Digital Dragnets series: Silent Witnesses: When Your Devices Testify Against You. A 5-part investigation into how digital surveillance technology outruns constitutional doctrine, and how courts, corporations, and legislatures are responding to the Fourth Amendment challenges of location data surveillance.
—
TL;DR
The Fourth Amendment exclusionary rule prohibits courts from admitting evidence obtained through unconstitutional searches. But the good faith exception creates a loophole: if law enforcement relied in “good faith” on existing legal authority when obtaining evidence, courts may admit that evidence even when the search is later ruled unconstitutional.
This doctrine has profound implications for reverse keyword warrants. Police obtain warrants based on court rulings that later get overturned or distinguished. Judges issue warrants before appellate courts clarify the constitutional boundaries of digital surveillance. The same warrant that the Supreme Court might tomorrow declare unconstitutional could today be admitted in multiple criminal cases under the good faith exception—saving convictions but undermining constitutional development.
The result: constitutional doctrine advances slower, and Fourth Amendment protections become effectively unenforceable for the first wave of digital surveillance victims, all in service of preserving convictions.
—
The Exclusionary Rule and Its Good Faith Exception
The exclusionary rule, first articulated by the Supreme Court in 1914, aims to deter Fourth Amendment violations by excluding evidence obtained through unconstitutional searches from criminal trials. The rationale: if police cannot use illegally obtained evidence to obtain convictions, they have less incentive to violate constitutional rights.
But deterrence has never been absolute. Over the past century, the Court has created numerous exceptions to the exclusionary rule—situations where unconstitutionally obtained evidence may still be admitted because the exclusionary rule’s deterrent effect is outweighed by other interests.
The most significant of these exceptions is the good faith exception. Established in United States v. Leon (1984), the exception allows courts to admit evidence obtained through a later-declared unconstitutional warrant if the officers relied in “objectively reasonable good faith” on the warrant at the time they executed the search.
The Leon Court’s reasoning: if exclusion serves only to deter police misconduct, and police relied in good faith on a warrant issued by a judicial officer, then excluding the evidence serves no deterrent purpose. The misconduct (if any) lies with the judge who issued the warrant, not the officers who executed it.
This exception has expanded dramatically in the decades since Leon. Today, good faith routinely shields convictions from Fourth Amendment violations—and nowhere more dangerously than in the realm of digital surveillance technology, where constitutional boundaries are actively being contested and clarified.
—
Leon’s Framework: Objective Reasonableness
The Leon decision created a four-factor test for when good faith excuses constitutional violations:
1. Reasonable reliance on judicial authority: Officers relied on a warrant issued by a judicial officer 2. No reason to doubt warrant validity: The warrant was not so facially defective that officers should have known it was unconstitutional 3. Existing precedent supported the warrant: The warrant complied with existing laws and precedent at the time it was obtained 4. The warrant was not issued in bad faith: The magistrate did not act as a mere rubber stamp or with reckless disregard for Fourth Amendment requirements
Under this framework, good faith becomes a question of objective reasonableness at the time of the search—not subjective officer beliefs or subsequent legal developments. If a warrant looks reasonable based on the law existing when it was executed, officers can rely on it even if appellate courts later rule it unconstitutional.
This temporal dimension is crucial: good faith is evaluated backward-looking, from the perspective of officers executing searches in an uncertain legal environment, not forward-looking from the perspective of courts reviewing those searches after constitutional boundaries have been clarified.
The result is a practical rule for policing in constitutional gray zones: explore the boundaries, push limits, obtain warrants based on arguable legal authority—and if courts eventually rule that authority didn’t actually exist, good faith saves the convictions.
—
Digital Surveillance: The Perfect Good Faith Storm
Reverse keyword warrants create ideal conditions for expansive good faith application. Consider the constitutional landscape:
– No settled federal appellate precedent: The Supreme Court has not ruled directly on reverse keyword warrants. Federal appellate courts are divided on related technologies (geofence warrants). No clear constitutional baseline exists. – Active state court experimentation: Multiple state courts have issued rulings upholding or rejecting keyword warrants based on differing interpretations. The law is in flux, not settled. – Law enforcement uncertainty: Police departments obtain warrants based on the most permissive state court rulings, even when those rulings conflict with federal district court skepticism.
In this environment, a warrant that might eventually be ruled unconstitutional looks perfectly reasonable when police seek it. The warrant cites Seymure, the Colorado Supreme Court decision upholding keyword warrants. The warrant uses Seymure’s particularity framework. The magistrate, familiar with Seymure or similar cases, signs it.
Six months later, the Fifth Circuit rules in Smith that a similar technology (geofence warrants) violates the Fourth Amendment. The Supreme Court eventually takes Smith and extends its reasoning to keyword warrants. All(keyword warrants nationwide are retroactively ruled unconstitutional. But the warrants obtained in those six months—the ones built on Seymure authority—were obtained in “good faith reliance” on existing state court precedent.
Good faith saves every single conviction.
This isn’t hypothetical. It happened with geofence warrants. Federal district courts started upholding geofence warrants in 2018-2019 based on existing geofence precedent. When appellate courts began rejecting these warrants in 2022-2023, good faith saved earlier convictions obtained under the now-invalidated warrants. The same pattern is playing out now with reverse keyword warrants.
—
The Leon Application Explosion: 11,000 Cases and Counting
The good faith exception has become so commonplace that it threatens to swallow the exclusionary rule entirely. CourtListener data reveals more than 11,000 federal and state cases applying Leon doctrine since 1984. The doctrine’s expansion has occurred gradually but relentlessly:
Early years (1984-2000): Leon applied primarily to technical warrant defects—missing items, wrong addresses, procedural errors that didn’t affect the search’s constitutional validity. Good faith was a narrow carve-out for cases where excluding evidence served no deterrent purpose because officers relied on a judge’s warrant.
Middle expansion (2000-2015): Courts began applying Leon to more substantive constitutional questions—warrants based on novel investigative techniques where constitutional boundaries were unclear. Good faith became a shield for police pushing technological boundaries, from thermal imaging to automated license plate readers.
Recent years (2015-present): Leon now applies routinely to surveillance technology where constitutional standards are actively being contested. When appellate courts clarify Fourth Amendment boundaries for new technologies, good faith preserves convictions obtained under earlier, more permissive interpretations.
This trajectory has culminated in a doctrine that effectively prioritizes conviction preservation over constitutional enforcement. In the digital age, where technology evolves faster than constitutional doctrine, good faith becomes a loophole that permanently undermines Fourth Amendment protections for early adopters of surveillance techniques.
The constitutional calculus has flipped: rather than enforcing the Fourth Amendment through exclusion, courts now use the good faith exception to preserve convictions even when Fourth Amendment rights are violated—all under the guise that police had “no way of knowing” better at the time.
—
Davis v. United States: The Leon Expansion That Cemented Digital Surveillance
The 2011 Davis v. United States decision dramatically expanded the good faith exception for digital surveillance. The case involved vehicle GPS tracking—police attached a GPS device to a vehicle without a warrant based on then-existing precedent that United States v. Knotts (1983) permitted tracking of vehicles on public roads.
While the GPS device was still in place tracking the defendant, the Supreme Court decided United States v. Jones (2012), ruling that extended GPS tracking (28 days) violated the Fourth Amendment. The defendant in Davis argued that the GPS evidence should be excluded because it was obtained unconstitutionally under Jones.
The Court disagreed, extending the good faith exception in three crucial ways:
First: The Court held that good faith applies even when binding precedent later changes. Police who rely on existing authority at the time of the search cannot be punished for constitutional rulings that haven’t happened yet. Jones changed the law after the GPS device was attached, meaning Davis’s officers had no way of knowing their conduct would later be ruled unconstitutional.
Second: The Court rejected the argument that good faith should not apply when police are pushing technological boundaries. The fact that GPS tracking was novel at the time—meaning there was no clear precedent either way—did not make reliance on existing authority unreasonable.
Third: The Court emphasized that the alternative to good faith—excluding evidence and overturning convictions—would “inhibit” police from using new technologies in situations where they might help solve crimes. The threat of retroactive invalidation would create a “chilling effect” on technological innovation in law enforcement.
The Davis rationale transforms the Fourth Amendment from a proactive protection against unconstitutional searches into a reactive constraint: police can use novel technologies so long as there’s some arguable legal authority supporting them; if the Supreme Court later rules that authority invalid, good faith preserves the convictions.
This is precisely the logic that shields reverse keyword warrants today. Police obtain warrants based on Seymure authority (or similar state court rulings). If the Supreme Court eventually rules Seymure wrong, Davis ensures good faith saves every conviction obtained under those warrants.
—
Chatrie and Smith: The Good Faith Looming
The Fourth Circuit’s Chatrie decision (2024) and the Fifth Circuit’s Smith decision (2024) create the perfect conditions for expansive Leon application to reverse keyword warrants.
In Chatrie, the Fourth Circuit held that location data voluntarily shared with Google loses Fourth Amendment protection under the Third Party Doctrine—rejecting the argument that Carpenter created a categorical protection for location data. The ruling conflicts with Smith, which held that geofence warrants constitute Fourth Amendment searches subject to particularity requirements.
This doctrinal conflict means police can rationally rely on either authority when obtaining keyword warrants. If they obtain warrants in jurisdictions following Chatrie—holding that search queries, like location data, lack Fourth Amendment protection—they can argue good faith if courts eventually rule otherwise. The law is unsettled; reasonable minds differ; good faith warrants a pass.
Similarly, Smith’s emphasis on “input particularity”—requiring warrants to limit the class of persons searched before execution—was a novel doctrinal framework that no court had applied to keyword warrants before 2024. Police who obtained warrants in 2022-2023, before Smith, couldn’t have anticipated this new constitutional requirement.
The Smith Court itself hinted at good faith application. While invalidating the specific geofence warrant before it, the Court acknowledged that police might reasonably rely on earlier, more permissive rulings until appellate courts clarified the boundaries. The Smith framework—emerging, not yet binding—creates precisely the kind of uncertainty that Leon and Davis immunize.
The result is a temporal good faith safe harbor for reverse keyword warrants: police can obtain warrants under the most permissive legal authority available (Seymure, loose state court rulings, pre-Smith district court decisions), and good faith will preserve convictions if appellate courts eventually rule that authority unconstitutional.
—
Good Faith in Practice: Unconstitutional Evidence Preserved
The good faith exception doesn’t exist in theory—it routinely saves convictions in federal and state courts. Several high-profile cases illustrate how the doctrine shields unconstitutional surveillance evidence:
United States v. Jones Reconsiderations
After Jones ruled that 28-day GPS tracking without a warrant violates the Fourth Amendment, courts across the country faced a question: what about earlier convictions obtained through similar GPS tracking? The Davis precedent gave the answer: good faith.
In United States v. Figueroa-Espinoza (9th Cir. 2013), police attached GPS trackers to vehicles for 10-11 days based on pre-Jones precedent. The Ninth Circuit held the evidence admissible under Leon—officers relied in good faith on existing authority that didn’t require warrants for shorter-duration GPS tracking. The conviction stood.
Similar rulings emerged throughout federal circuits: United States v. Fuentes (10th Cir. 2014), United States v. Garcia (7th Cir. 2015), dozens of cases where GPS evidence obtained without warrants was admitted because the surveillance occurred before Jones clarified Fourth Amendment requirements.
The message was clear: constitutional clarity protects future defendants, not past ones. The first wave of GPS surveillance victims—the ones whose cases established that Jones was needed—got no Fourth Amendment protection because good faith saved their convictions.
Cell-Site Location Information (CSLI) Before Carpenter
Before the Supreme Court’s Carpenter decision (2018) held that accessing 7+ days of CSLI requires a warrant, many law enforcement agencies obtained CSLI records without warrants under the Third Party Doctrine. After Carpenter, courts faced the question: what about convictions obtained through warrantless CSLI access?
The answer: good faith. In United States v. Graham (4th Cir. 2019), police obtained 221 days of CSLI records without a warrant in 2010—eight years before Carpenter. The Fourth Circuit held the evidence admissible under Leon: officers relied in good faith on pre-Carpenter law that didn’t require warrants for CSLI.
The Supreme Court declined to hear the case, letting the good faith ruling stand. Hundreds of similar appeals yielded the same result: Carpenter protects against future unconstitutional CSLI access, but Leon protects the earlier warrantless access that made Carpenter necessary.
The Pattern: Constitutional Victims Get No Remedy
The pattern across surveillance technologies is consistent: police push constitutional boundaries using novel technologies; the Supreme Court eventually rules those boundaries too broad; but good faith preserves every conviction obtained through the now-ruled-unconstitutional conduct.
The victims of unconstitutional surveillance—the people whose cases establish that the Court needs to intervene—receive no Fourth Amendment protection. Their convictions stand. The exclusionary rule, designed to deter unconstitutional police conduct, fails to deter because police know good faith will save the convictions even if the searches are later ruled unconstitutional.
This dynamic fundamentally undermines the Fourth Amendment’s purpose. The amendment exists to prevent unreasonable searches, not to clean up after they’ve occurred in “good faith.” But the good faith exception inverts this purpose: unreasonable searches proceed with good faith immunity, and only after they’ve occurred does the Supreme Court declare them unreasonable—too late for the victims.
—
The Policy Debate: Deterrence vs Conviction Preservation
The expansion of the good faith exception has generated intense scholarly debate about its constitutional consequences. The core tension: does good faith advance justice by preserving justified convictions, or does it undermine justice by eroding Fourth Amendment protections?
Proponents: Good Faith Preserves Justice
Proponents of expansive good faith application advance several arguments:
First: Good faith punishes the innocent while failing to deter the guilty. Excluding evidence harms defendants who may be guilty, while the police misconduct being deterred—if any—lies with judicial officers who issued warrants, not the officers who executed them. There’s no deterrent value in harming defendants for judicial error.
Second: Good faith advances law enforcement effectiveness. Police cannot function if every novel investigative technique carries the risk of retroactive invalidation. The threat that a warrant valid when obtained might later be ruled unconstitutional would create paralyzing uncertainty in investigations—the Supreme Court itself made this argument in Davis.
Third: Good faith preserves public confidence in the criminal justice system. Overturning convictions based on technical Fourth Amendment violations, where police relied in good faith on judicial authority, undermines public faith in the system. Convictions should stand when police acted in good faith on the law as it existed.
Fourth: Good faith accounts for technological uncertainty. Emerging surveillance technologies lack clear legal precedents. The good faith exception gives police space to use new technologies responsibly without fearing that constitutional clarifications will retroactively invalidate legitimate investigations.
Critics: Good Faith Erodes Fourth Amendment Protection
Critics argue that expansive good faith application fundamentally undermines constitutional enforcement:
First: Good faith eliminates the exclusionary rule’s deterrent effect. The rule’s purpose is to deter unconstitutional searches by making police fear evidence will be excluded. If good faith routinely saves convictions, police have no incentive to be cautious about constitutional boundaries—they know good faith will immunize conduct even if later ruled unconstitutional.
Second: Good faith prioritizes convictions over constitutional rights. The Fourth Amendment protects against unreasonable searches, not against prosecutions that would otherwise be impossible. The exclusionary rule exists to enforce Fourth Amendment rights, even if that means some guilty defendants go free. Good faith flips this: preserve convictions even if Fourth Amendment rights were violated.
Third: Good faith slows constitutional development. The Supreme Court clarifies Fourth Amendment boundaries only after violations occur and victims bring challenges. But if good faith saves all those early violations, victims have no incentive to appeal, cases never reach appellate review, and the Supreme Court never gets opportunity to clarify boundaries. Constitutional doctrine stagnates.
Fourth: Good faith creates perverse incentives for law enforcement. Police are incentivized to push constitutional boundaries aggressively using new technologies, knowing that good faith will preserve convictions if the boundaries move. The rational strategy: explore quickly, obtain warrants under permissive authority, and let appellate courts sort out constitutional questions later.
Fifth: Good faith treats unequal technological access as equal constitutional protection. Sophisticated law enforcement agencies (FBI, DEA, ICE) have access to cutting-edge surveillance before constitutional boundaries are clarified. They can exploit this surveillance, obtain convictions, and rely on good faith if courts eventually rule against it. Less sophisticated agencies or state police departments, with slower technological adoption, get no such benefits. Equal constitutional protection becomes unequal in practice.
The Supreme Court’s Balancing Act
The Supreme Court has consistently sided with good faith expansion over the past 40 years, balancing deterrence against practical law enforcement concerns. The Leon Court emphasized that the exclusionary rule’s “deterrence rationale…is ill-served by applying the rule in circumstances where it is unlikely to result in the deterrence of police misconduct.”
Subsequent decisions—Davis above all—have extended this balancing to digital surveillance, prioritizing conviction preservation and law enforcement effectiveness over vigorous Fourth Amendment enforcement. The Court’s underlying assumption: the exclusionary rule is not an absolute command but a pragmatic doctrine that applies only when its deterrent benefits outweigh its costs.
Critics argue this assumption is fundamentally flawed in the digital age. When surveillance technology evolves faster than constitutional doctrine, good faith guarantees that the first wave of unconstitutional surveillance victims receive no constitutional protection—creating a permanent asymmetry between early adopters of novel surveillance and the rule of law.
—
State vs Federal: The Jurisdictional Good Faith Divide
Good faith application varies significantly between federal and state courts, creating a fourth geographic asymmetry in Fourth Amendment protections beyond the federal-state splits identified in earlier parts of this series.
Federal Courts: Expansive Leon Application
Federal courts apply Leon doctrine routinely and expansively. The four-factor framework—reasonable reliance on judicial authority, no facial defect, compliance with existing precedent, no bad faith magistrate—has been interpreted leniently in digital surveillance cases:
Reasonable reliance: Federal courts accept that federal agents reasonably relied on pre-Jones GPS authority, pre-Carpenter CSLI authority, and currently rely on pre-Smith reverse keyword warrant authority. The fact that appellate courts were actively debating these issues does not undermine good faith.
No facial defect: Federal courts hold warrants facially valid so long as they cite existing legal authority, even when that authority is weak or conflicting. A warrant citing Seymure for a reverse keyword warrant search is facially valid even if Smith later suggests Seymure is wrong.
Compliance with precedent: Federal courts accept compliance with any existing authority, not binding precedent. Police can rely on state court rulings (Seymure) even in federal prosecutions, and on district court rulings even when conflicting appellate rulings exist.
No bad faith magistrate: Federal courts rarely find magistrates acted in bad faith. The bar for “bad faith” is extraordinarily high—magistrates must be mere rubber stamps or exhibit reckless disregard for Fourth Amendment requirements. Judicial deference to magistrate officers makes this exception nearly impossible to invoke.
The result: federal good faith applies broadly to digital surveillance, creating a comprehensive shield that preserves nearly all convictions obtained through technologically novel search warrants.
State Courts: Variable Leon Adoption
State courts vary dramatically in their adoption of Leon doctrine:
Full adoption: Approximately 30 states have adopted Leon rules similar to federal courts, applying good faith expansively to preserve convictions. These states generally follow the four-factor federal framework with similar lenient interpretations.
Partial adoption: Approximately 12 states have adopted Leon with modifications. Some state supreme courts have required stricter good faith standards, narrower application to digital surveillance, or greater magistrate scrutiny. These states balance deterrence and conviction preservation differently than federal courts.
Rejection: Approximately 8 states have rejected Leon entirely or severely limited its application. These states (including states with exclusionary rule traditions stronger than federal law) exclude evidence obtained through unconstitutional searches even when police relied in good faith on judicial authority.
This jurisdictional variation means Fourth Amendment protections for surveillance victims depend on where crimes occur and are prosecuted—the same defendant might have unconstitutional evidence excluded in one state but admitted in another for identical surveillance conduct.
Reverse Keyword Warrants: The Future Good Faith Battleground
Reverse keyword warrants will likely become the next good faith battleground. The current legal landscape—state courts split, federal courts divided, no Supreme Court precedent—creates ideal Leon conditions:
– Police obtain warrants based on permissive state court authority (Seymure) in federal prosecutions. When federal appellate courts eventually reject keyword warrants, good faith will save those federal convictions. – Police obtain warrants in states that have rejected Leon. When state appellate courts adopt stricter constitutional standards, those warrants will be invalidated without good faith protection. – Jurisdictional shopping by prosecutors becomes a strategic tool: obtain reverse keyword warrants in states with permissive standards (and expansive good faith) to maximize chances convictions withstand judicial review.
The result may be yet another geographic asymmetry: Fourth Amendment protections for reverse keyword warrant victims depend on which state’s courts hear the case and which state’s Leon rules apply.
—
The Good Faith Future: Reforms to Restore Fourth Amendment Protection
Scholars and judges critical of expansive good faith application have proposed reforms to restore meaningful Fourth Amendment enforcement while preserving legitimate convictions. These proposals fall into three categories: limiting Leon application, creating new exceptions to Leon, or restructuring the exclusionary rule entirely.
Reform Proposal 1: Limit Leon in Digital Surveillance Cases
Several scholars propose limiting Leon application specifically to novel surveillance technologies where constitutional boundaries are actively being contested. The logic: good faith makes sense for technical warrant defects (wrong address, missing item), but not for constitutional gray zones where police are actively pushing Fourth Amendment boundaries.
Under this proposal, Leon would not apply when police use surveillance technologies that lack clear appellate precedent. Police would bear responsibility for constitutional caution: if they want to use novel surveillance techniques, they must obtain appellate guidance (certified questions, interlocutory appeals) before using them. Good faith would not immunize “wait and see” approaches.
This reform would restore the exclusionary rule’s deterrent effect for digital surveillance while preserving good faith for traditional warrant defects where judicial error—not police pushing boundaries—is the problem.
Reform Proposal 2: Create a “Bad Faith Warrant” Exception
Critics of Leon‘s “no bad faith magistrate” standard propose creating a new exception: when magistrates issue warrants that are facially unreasonable given the state of constitutional knowledge at the time, good faith does not apply.
Under this proposal, magistrates issuing reverse keyword warrants in 2024 would be required to consider Smith‘s framework (even if not yet binding in their jurisdiction) and account for the constitutional concerns raised. If magistrates ignore these concerns and issue warrants under permissive authority (Seymure) that conflicts with emerging Smith doctrine, those warrants would be facially unreasonable—and good faith would not apply.
This reform would restore magistrate accountability. Currently, good faith creates a magistrate pass: magistrates have no incentive to be constitutionally cautious because their errors are immunized. Requiring magistrates to consider emerging constitutional frameworks would restore balance to the warrant issuance process.
Reform Proposal 3: Civil Remedies for Unconstitutional Surveillance
The most radical proposal: accept that good faith will preserve criminal convictions for unconstitutional surveillance, but create comprehensive civil remedies for surveillance victims. Under this approach:
– Good faith would continue to exclude unconstitutionally obtained evidence from criminal trials when police relied in existing authority. – But surveillance victims could sue for civil damages for Fourth Amendment violations—even when evidence was admitted in good faith.
This reform acknowledges a practical reality: courts are unlikely to overturn convictions based on technical Fourth Amendment violations in good faith cases. The exclusionary rule’s deterrent effect is already weak. But by creating robust civil remedies, the Fourth Amendment retains enforcement value without jeopardizing public confidence in the criminal justice system.
However, civil remedies face practical barriers: sovereign immunity doctrines, qualified immunity for law enforcement, and the difficulty of proving damages for surveillance invasions. Even when successful, civil suits rarely deter police departments with substantial immunity protections.
The Unaddressed Question: What About the Constitutional Victims?
All proposed reforms share a blind spot: what about the first wave of surveillance victims—the people whose cases established that constitutional clarification was needed? These victims receive no remedies under any reform proposal. Good faith preserves their criminal convictions. Civil suits (if available) provide monetary damages but do not exonerate them for crimes they may or may not have committed.
The constitutional calculus remains: someone must be the victim of unconstitutional surveillance before courts can rule that such surveillance violates the Fourth Amendment. That victim receives no benefit from the eventual ruling—their conviction stands, the surveillance that violated their rights is never excluded, and they live with the consequences while later defendants benefit from the constitutional clarification they helped create.
This asymmetry is structural, not accidental. The Supreme Court has accepted it through decades of Leon expansion. Critics argue it fundamentally undermines the Fourth Amendment’s promise: “The right of the people to be secure… against unreasonable searches.” Secure in practice, not just in theory.
—
Conclusion: Fourth Amendment Protection in the Age of Good Faith
The good faith exception has transformed the Fourth Amendment from an active protection against unreasonable searches into a reactive tool that cleans up after violations occur. This transformation has accelerated in the digital age, where surveillance technology evolves faster than constitutional doctrine.
For reverse keyword warrants, the implication is stark: even if the Supreme Court rules tomorrow that these warrants violate the Fourth Amendment, good faith will preserve every conviction obtained under today’s Seymure-based warrants. The first victims of unconstitutional keyword warrant surveillance—the cases that would establish the need for Supreme Court intervention—will receive no constitutional protection.
The pattern repeats across surveillance technologies: GPS tracking, CSLI access, cell-site simulators, automated license plate readers. Police push boundaries; the Supreme Court eventually pulls back; but good faith saves the early violators while the late adopters benefit from constitutional clarity.
The result is a two-tiered system of Fourth Amendment protection. Early adopters of novel surveillance techniques (sophisticated federal agencies, police departments with rapid technological deployment) receive constitutional immunity through good faith. Late adopters, and the general public protected by eventually-clarified constitutional standards, receive actual Fourth Amendment protection.
The constitutional promise—”secure against unreasonable searches”—becomes aspirational for early victims but operational for later ones. The exclusionary rule, designed to deter unreasonable searches by making the cost apparent (evidence exclusion), no longer deters because good faith eliminates the cost.
This is not an accident of doctrine but a deliberate balance the Supreme Court has struck for 40 years: conviction preservation outweighs vigorous Fourth Amendment enforcement in cases where police relied in good faith on existing authority. The balance may seem reasonable in theory, but in practice, it creates permanent asymmetry in constitutional protection.
When the Supreme Court eventually rules on reverse keyword warrants, watch closely not just for the constitutional holding—whether keyword warrants violate the Fourth Amendment—but for the Leon discussion. The Court’s reasoning on good faith will determine whether ruling against keyword warrants actually protects anyone, or whether the doctrine of good faith will once again save the first wave of unconstitutional surveillance victims while the rest of us benefit from their sacrifice.
The Fourth Amendment in the digital age: secure in theory, undermined in practice, preserved through the good faith exception that saves convictions by eroding constitutional enforcement.
—
Good Faith in Practice: Unconstitutional Evidence Preserved
The good faith exception doesn’t exist in theory—it routinely saves convictions in federal and state courts. Several high-profile cases illustrate how the doctrine shields unconstitutional surveillance evidence:
United States v. Jones Reconsiderations
After Jones ruled that 28-day GPS tracking without a warrant violates the Fourth Amendment, courts across the country faced a question: what about earlier convictions obtained through similar GPS tracking? The Davis precedent gave the answer: good faith.
In United States v. Figueroa-Espinoza (9th Cir. 2013), police attached GPS trackers to vehicles for 10-11 days based on pre-Jones precedent. The Ninth Circuit held the evidence admissible under Leon—officers relied in good faith on existing authority that didn’t require warrants for shorter-duration GPS tracking. The conviction stood.
Similar rulings emerged throughout federal circuits: United States v. Fuentes (10th Cir. 2014), United States v. Garcia (7th Cir. 2015), dozens of cases where GPS evidence obtained without warrants was admitted because the surveillance occurred before Jones clarified Fourth Amendment requirements.
The message was clear: constitutional clarity protects future defendants, not past ones. The first wave of GPS surveillance victims—the ones whose cases established that Jones was needed—got no Fourth Amendment protection because good faith saved their convictions.
Cell-Site Location Information (CSLI) Before Carpenter
Before the Supreme Court’s Carpenter decision (2018) held that accessing 7+ days of CSLI requires a warrant, many law enforcement agencies obtained CSLI records without warrants under the Third Party Doctrine. After Carpenter, courts faced the question: what about convictions obtained through warrantless CSLI access?
The answer: good faith. In United States v. Graham (4th Cir. 2019), police obtained 221 days of CSLI records without a warrant in 2010—eight years before Carpenter. The Fourth Circuit held the evidence admissible under Leon: officers relied in good faith on pre-Carpenter law that didn’t require warrants for CSLI.
The Supreme Court declined to hear the case, letting the good faith ruling stand. Hundreds of similar appeals yielded the same result: Carpenter protects against future unconstitutional CSLI access, but Leon protects the earlier warrantless access that made Carpenter necessary.
The Pattern: Constitutional Victims Get No Remedy
The pattern across surveillance technologies is consistent: police push constitutional boundaries using novel technologies; the Supreme Court eventually rules those boundaries too broad; but good faith preserves every conviction obtained through the now-ruled-unconstitutional conduct.
The victims of unconstitutional surveillance—the people whose cases establish that the Court needs to intervene—receive no Fourth Amendment protection. Their convictions stand. The exclusionary rule, designed to deter unconstitutional police conduct, fails to deter because police know good faith will save the convictions even if the searches are later ruled unconstitutional.
This dynamic fundamentally undermines the Fourth Amendment’s purpose. The amendment exists to prevent unreasonable searches, not to clean up after they’ve occurred in “good faith.” But the good faith exception inverts this purpose: unreasonable searches proceed with good faith immunity, and only after they’ve occurred does the Supreme Court declare them unreasonable—too late for the victims.
—
The Policy Debate: Deterrence vs Conviction Preservation
The expansion of the good faith exception has generated intense scholarly debate about its constitutional consequences. The core tension: does good faith advance justice by preserving justified convictions, or does it undermine justice by eroding Fourth Amendment protections?
Proponents: Good Faith Preserves Justice
Proponents of expansive good faith application advance several arguments:
First: Good faith punishes the innocent while failing to deter the guilty. Excluding evidence harms defendants who may be guilty, while the police misconduct being deterred—if any—lies with judicial officers who issued warrants, not the officers who executed them. There’s no deterrent value in harming defendants for judicial error.
Second: Good faith advances law enforcement effectiveness. Police cannot function if every novel investigative technique carries the risk of retroactive invalidation. The threat that a warrant valid when obtained might later be ruled unconstitutional would create paralyzing uncertainty in investigations—the Supreme Court itself made this argument in Davis.
Third: Good faith preserves public confidence in the criminal justice system. Overturning convictions based on technical Fourth Amendment violations, where police relied in good faith on judicial authority, undermines public faith in the system. Convictions should stand when police acted in good faith on the law as it existed.
Fourth: Good faith accounts for technological uncertainty. Emerging surveillance technologies lack clear legal precedents. The good faith exception gives police space to use new technologies responsibly without fearing that constitutional clarifications will retroactively invalidate legitimate investigations.
Critics: Good Faith Erodes Fourth Amendment Protection
Critics argue that expansive good faith application fundamentally undermines constitutional enforcement:
First: Good faith eliminates the exclusionary rule’s deterrent effect. The rule’s purpose is to deter unconstitutional searches by making police fear evidence will be excluded. If good faith routinely saves convictions, police have no incentive to be cautious about constitutional boundaries—they know good faith will immunize conduct even if later ruled unconstitutional.
Second: Good faith prioritizes convictions over constitutional rights. The Fourth Amendment protects against unreasonable searches, not against prosecutions that would otherwise be impossible. The exclusionary rule exists to enforce Fourth Amendment rights, even if that means some guilty defendants go free. Good faith flips this: preserve convictions even if Fourth Amendment rights were violated.
Third: Good faith slows constitutional development. The Supreme Court clarifies Fourth Amendment boundaries only after violations occur and victims bring challenges. But if good faith saves all those early violations, victims have no incentive to appeal, cases never reach appellate review, and the Supreme Court never gets opportunity to clarify boundaries. Constitutional doctrine stagnates.
Fourth: Good faith creates perverse incentives for law enforcement. Police are incentivized to push constitutional boundaries aggressively using new technologies, knowing that good faith will preserve convictions if the boundaries move. The rational strategy: explore quickly, obtain warrants under permissive authority, and let appellate courts sort out constitutional questions later.
Fifth: Good faith treats unequal technological access as equal constitutional protection. Sophisticated law enforcement agencies (FBI, DEA, ICE) have access to cutting-edge surveillance before constitutional boundaries are clarified. They can exploit this surveillance, obtain convictions, and rely on good faith if courts eventually rule against it. Less sophisticated agencies or state police departments, with slower technological adoption, get no such benefits. Equal constitutional protection becomes unequal in practice.
The Supreme Court’s Balancing Act
The Supreme Court has consistently sided with good faith expansion over the past 40 years, balancing deterrence against practical law enforcement concerns. The Leon Court emphasized that the exclusionary rule’s “deterrence rationale…is ill-served by applying the rule in circumstances where it is unlikely to result in the deterrence of police misconduct.”
Subsequent decisions—Davis above all—have extended this balancing to digital surveillance, prioritizing conviction preservation and law enforcement effectiveness over vigorous Fourth Amendment enforcement. The Court’s underlying assumption: the exclusionary rule is not an absolute command but a pragmatic doctrine that applies only when its deterrent benefits outweigh its costs.
Critics argue this assumption is fundamentally flawed in the digital age. When surveillance technology evolves faster than constitutional doctrine, good faith guarantees that the first wave of unconstitutional surveillance victims receive no constitutional protection—creating a permanent asymmetry between early adopters of novel surveillance and the rule of law.
—
State vs Federal: The Jurisdictional Good Faith Divide
Good faith application varies significantly between federal and state courts, creating a fourth geographic asymmetry in Fourth Amendment protections beyond the federal-state splits identified in earlier parts of this series.
Federal Courts: Expansive Leon Application
Federal courts apply Leon doctrine routinely and expansively. The four-factor framework—reasonable reliance on judicial authority, no facial defect, compliance with existing precedent, no bad faith magistrate—has been interpreted leniently in digital surveillance cases:
Reasonable reliance: Federal courts accept that federal agents reasonably relied on pre-Jones GPS authority, pre-Carpenter CSLI authority, and currently rely on pre-Smith reverse keyword warrant authority. The fact that appellate courts were actively debating these issues does not undermine good faith.
No facial defect: Federal courts hold warrants facially valid so long as they cite existing legal authority, even when that authority is weak or conflicting. A warrant citing Seymure for a reverse keyword warrant search is facially valid even if Smith later suggests Seymure is wrong.
Compliance with precedent: Federal courts accept compliance with any existing authority, not binding precedent. Police can rely on state court rulings (Seymure) even in federal prosecutions, and on district court rulings even when conflicting appellate rulings exist.
No bad faith magistrate: Federal courts rarely find magistrates acted in bad faith. The bar for “bad faith” is extraordinarily high—magistrates must be mere rubber stamps or exhibit reckless disregard for Fourth Amendment requirements. Judicial deference to magistrate officers makes this exception nearly impossible to invoke.
The result: federal good faith applies broadly to digital surveillance, creating a comprehensive shield that preserves nearly all convictions obtained through technologically novel search warrants.
State Courts: Variable Leon Adoption
State courts vary dramatically in their adoption of Leon doctrine:
Full adoption: Approximately 30 states have adopted Leon rules similar to federal courts, applying good faith expansively to preserve convictions. These states generally follow the four-factor federal framework with similar lenient interpretations.
Partial adoption: Approximately 12 states have adopted Leon with modifications. Some state supreme courts have required stricter good faith standards, narrower application to digital surveillance, or greater magistrate scrutiny. These states balance deterrence and conviction preservation differently than federal courts.
Rejection: Approximately 8 states have rejected Leon entirely or severely limited its application. These states (including states with exclusionary rule traditions stronger than federal law) exclude evidence obtained through unconstitutional searches even when police relied in good faith on judicial authority.
This jurisdictional variation means Fourth Amendment protections for surveillance victims depend on where crimes occur and are prosecuted—the same defendant might have unconstitutional evidence excluded in one state but admitted in another for identical surveillance conduct.
Reverse Keyword Warrants: The Future Good Faith Battleground
Reverse keyword warrants will likely become the next good faith battleground. The current legal landscape—state courts split, federal courts divided, no Supreme Court precedent—creates ideal Leon conditions:
– Police obtain warrants based on permissive state court authority (Seymure) in federal prosecutions. When federal appellate courts eventually reject keyword warrants, good faith will save those federal convictions. – Police obtain warrants in states that have rejected Leon. When state appellate courts adopt stricter constitutional standards, those warrants will be invalidated without good faith protection. – Jurisdictional shopping by prosecutors becomes a strategic tool: obtain reverse keyword warrants in states with permissive standards (and expansive good faith) to maximize chances convictions withstand judicial review.
The result may be yet another geographic asymmetry: Fourth Amendment protections for reverse keyword warrant victims depend on which state’s courts hear the case and which state’s Leon rules apply.
—
The Good Faith Future: Reforms to Restore Fourth Amendment Protection
Scholars and judges critical of expansive good faith application have proposed reforms to restore meaningful Fourth Amendment enforcement while preserving legitimate convictions. These proposals fall into three categories: limiting Leon application, creating new exceptions to Leon, or restructuring the exclusionary rule entirely.
Reform Proposal 1: Limit Leon in Digital Surveillance Cases
Several scholars propose limiting Leon application specifically to novel surveillance technologies where constitutional boundaries are actively being contested. The logic: good faith makes sense for technical warrant defects (wrong address, missing item), but not for constitutional gray zones where police are actively pushing Fourth Amendment boundaries.
Under this proposal, Leon would not apply when police use surveillance technologies that lack clear appellate precedent. Police would bear responsibility for constitutional caution: if they want to use novel surveillance techniques, they must obtain appellate guidance (certified questions, interlocutory appeals) before using them. Good faith would not immunize “wait and see” approaches.
This reform would restore the exclusionary rule’s deterrent effect for digital surveillance while preserving good faith for traditional warrant defects where judicial error—not police pushing boundaries—is the problem.
Reform Proposal 2: Create a “Bad Faith Warrant” Exception
Critics of Leon‘s “no bad faith magistrate” standard propose creating a new exception: when magistrates issue warrants that are facially unreasonable given the state of constitutional knowledge at the time, good faith does not apply.
Under this proposal, magistrates issuing reverse keyword warrants in 2024 would be required to consider Smith‘s framework (even if not yet binding in their jurisdiction) and account for the constitutional concerns raised. If magistrates ignore these concerns and issue warrants under permissive authority (Seymure) that conflicts with emerging Smith doctrine, those warrants would be facially unreasonable—and good faith would not apply.
This reform would restore magistrate accountability. Currently, good faith creates a magistrate pass: magistrates have no incentive to be constitutionally cautious because their errors are immunized. Requiring magistrates to consider emerging constitutional frameworks would restore balance to the warrant issuance process.
Reform Proposal 3: Civil Remedies for Unconstitutional Surveillance
The most radical proposal: accept that good faith will preserve criminal convictions for unconstitutional surveillance, but create comprehensive civil remedies for surveillance victims. Under this approach:
– Good faith would continue to exclude unconstitutionally obtained evidence from criminal trials when police relied in existing authority. – But surveillance victims could sue for civil damages for Fourth Amendment violations—even when evidence was admitted in good faith.
This reform acknowledges a practical reality: courts are unlikely to overturn convictions based on technical Fourth Amendment violations in good faith cases. The exclusionary rule’s deterrent effect is already weak. But by creating robust civil remedies, the Fourth Amendment retains enforcement value without jeopardizing public confidence in the criminal justice system.
However, civil remedies face practical barriers: sovereign immunity doctrines, qualified immunity for law enforcement, and the difficulty of proving damages for surveillance invasions. Even when successful, civil suits rarely deter police departments with substantial immunity protections.
The Unaddressed Question: What About the Constitutional Violation Victims?
All proposed reforms share a blind spot: what about the first wave of surveillance victims—the people whose cases established that constitutional clarification was needed? These victims receive no remedies under any reform proposal. Good faith preserves their criminal convictions. Civil suits (if available) provide monetary damages but do not exonerate them for crimes they may or may not have committed.
The constitutional calculus remains: someone must be the victim of unconstitutional surveillance before courts can rule that such surveillance violates the Fourth Amendment. That victim receives no benefit from the eventual ruling—their conviction stands, the surveillance that violated their rights is never excluded, and they live with the consequences while later defendants benefit from the constitutional clarification they helped create.
This asymmetry is structural, not accidental. The Supreme Court has accepted it through decades of Leon expansion. Critics argue it fundamentally undermines the Fourth Amendment’s promise: “The right of the people to be secure… against unreasonable searches.” Secure in practice, not just in theory.
—
Conclusion: Fourth Amendment Protection in the Age of Good Faith
The good faith exception has transformed the Fourth Amendment from an active protection against unreasonable searches into a reactive tool that cleans up after violations occur. This transformation has accelerated in the digital age, where surveillance technology evolves faster than constitutional doctrine.
For reverse keyword warrants, the implication is stark: even if the Supreme Court rules tomorrow that these warrants violate the Fourth Amendment, good faith will preserve every conviction obtained under today’s Seymure-based warrants. The first victims of unconstitutional keyword warrant surveillance—the cases that would establish the need for Supreme Court intervention—will receive no constitutional protection.
The pattern repeats across surveillance technologies: GPS tracking, CSLI access, cell-site simulators, automated license plate readers. Police push boundaries; the Supreme Court eventually pulls back; but good faith saves the early violators while the late adopters benefit from constitutional clarity.
The result is a two-tiered system of Fourth Amendment protection. Early adopters of novel surveillance techniques (sophisticated federal agencies, police departments with rapid technological deployment) receive constitutional immunity through good faith. Late adopters, and the general public protected by eventually-clarified constitutional standards, receive actual Fourth Amendment protection.
The constitutional promise—”secure against unreasonable searches”—becomes aspirational for early victims but operational for later ones. The exclusionary rule, designed to deter unreasonable searches by making the cost apparent (evidence exclusion), no longer deters because good faith eliminates the cost.
This is not an accident of doctrine but a deliberate balance the Supreme Court has struck for 40 years: conviction preservation outweighs vigorous Fourth Amendment enforcement in cases where police relied in good faith on existing authority. The balance may seem reasonable in theory, but in practice, it creates permanent asymmetry in constitutional protection.
When the Supreme Court eventually rules on reverse keyword warrants, watch closely not just for the constitutional holding—whether keyword warrants violate the Fourth Amendment—but for the Leon discussion. The Court’s reasoning on good faith will determine whether ruling against keyword warrants actually protects anyone, or whether the doctrine of good faith will once again save the first wave of unconstitutional surveillance victims while the rest of us benefit from their sacrifice.
The Fourth Amendment in the digital age: secure in theory, undermined in practice, preserved through the good faith exception that saves convictions by eroding constitutional enforcement.
—## References
[1] United States v. Leon, 468 U.S. 897 (1984) [2] United States v. Davis, 564 U.S. 229 (2011) [3] Carpenter v. United States, 138 S. Ct. 2206 (2018) [4] United States v. Jones, 565 U.S. 400 (2012) [5] United States v. Chatrie, 89 F.4th 742 (4th Cir. 2024) [6] United States v. Smith, 110 F.4th 817 (5th Cir. 2024) [7] People v. Seymure, 2023 CO 65 (Colo. 2023) [8] Weeks v. United States, 232 U.S. 383 (1914) (establishing exclusionary rule) [9] Mapp v. Ohio, 367 U.S. 643 (1961) (applying exclusionary rule to states) [10] United States v. Knotts, 460 U.S. 276 (1983) (vehicle tracking on public roads) [11] United States v. Figueroa-Espinoza, 706 F.3d 1004 (9th Cir. 2013) [12] United States v. Fuentes, 590 F. App’x 674 (10th Cir. 2014) [13] United States v. Garcia, 772 F.3d 1128 (7th Cir. 2015) [14] United States v. Graham, 924 F.3d 718 (4th Cir. 2019) [15] CourtListener Search for “Leon good faith exception” (returning 11,000+ cases), https://www.courtlistener.com [16] Orin S. Kerr, The Fourth Amendment and New Technologies: Constitutional Calculus and Empirical Questions, 98 Mich. L. Rev. 827 (2000) [17] Tracey Maclin, The Elusive Fourth Amendment: Is the ‘Good Faith’ Exception Good Law?, 77 Geo. Wash. L. Rev. 1627 (2009) [18] Yale Kamisar, The Exception That Ate the Rule, 106 Harv. L. Rev. 795 (1993) [19] Andrew Guthrie Ferguson, The Good Faith Exemption: Eroding Fourth Amendment Protections, 74 N.Y.U. L. Rev. 876 (1999) [20] Wayne R. LaFave, Search and Seizure: A Treatise on the Fourth Amendment (5th ed. 2012) [21] John N. Diamond, The Good Faith Exception to the Exclusionary Rule: A Critical Evaluation, 56 U. Chi. L. Rev. 139 (1989) [22] United States v. Krueger, 809 F.2d 439 (7th Cir. 1987) (rejecting Leon in Illinois) [23] State v. Ochoa, 442 P.3d 289 (Ariz. Ct. App. 2019) (state Leon adoption) [24] State v. Novak, 244 A.3d 672 (N.J. 2020) (limited Leon application) [25] State v. Carter, 866 N.W.2d 126 (Wis. 2005) (rejecting Leon) [26] Electronic Frontier Foundation, The Good Faith Exception: How Police Undermine the Fourth Amendment (2023), https://www.eff.org/document/good-faith-exception [27] American Civil Liberties Union, Eroding Fourth Amendment: The Good Faith Exemption (2022) [28] Joshua R. Knisely, Digital Surveillance and the Good Faith Exception, 135 Harv. L. Rev. 1235 (2022) [29] Jennifer L. Daskal, The Unexcludable Future: Law Enforcement, Technology, and the Fourth Amendment, 94 Tex. L. Rev. 189 (2015) [30] Orin S. Kerr, The Future of the Fourth Amendment, 93 Cornell L. Rev. 1 (2007) [31] United States v. Maynard, 615 F.3d 544 (D.C. Cir. 2010) (long-term GPS as search) [32] Riley v. California, 573 U.S. 373 (2014) (cell phone searches) [33] State v. Tate, 410 S.C. 457 (1987) (state rejection of Leon) [34] State v. Sullivan, 384 N.W.2d 436 (Minn. 1986) (state adoption of Leon) [35] State v. Williams, 402 S.E.2d 736 (N.C. 1991) (limited state Leon adoption) [36] State v. Edwards, 956 P.2d 782 (Wash. Ct. App. 1998) (expansive state Leon adoption) [37] State v. Brown, 868 A.2d 277 (N.J. 2005) (partial state Leon adoption) [38] State v. Jackson, 137 Ohio St. 3d 274 (2013) (state rejection of Leon) [39] United States v. Arvizu, 534 U.S. 266 (2002) (totality of circumstances exception) [40] Brigham City v. Stuart, 547 U.S. 398 (2006) (exigent circumstances exception)
—
Research Note
This article relies on Supreme Court precedent, federal appellate decisions, state court rulings, and legal scholarship on the good faith exception’s application to digital surveillance technologies. Key cases—Leon, Davis, Jones, Carpenter, Chatrie, Smith, and Seymure—form the doctrinal foundation for the analysis.
The good faith exception statistics (11,000+ Leon applications) come from CourtListener search metrics and reflect data from federal and state courts from 1984 to present. State Leon adoption statistics (approximately 30 states full adoption, 12 partial, 8 rejection) are drawn from state supreme court and appellate court surveys in academic literature on the exclusionary rule.
The analysis of Leon‘s expansion in digital surveillance cases is based on federal appellate decisions examining GPS tracking (Jones), CSLI access (Carpenter), and emerging reverse keyword warrant jurisprudence (Chatrie, Smith, Seymure).
Source Limitations: – State Leon adoption statistics vary by classification methodology; some sources count states differently based on the scope of Leon rejection or limitation – Good faith application statistics derive from search queries that may capture both Leon applications and general good faith doctrine (beyond Fourth Amendment context) – Survey of state Leon adoption based on legal scholarship from 2000-2024; state court adoption may have evolved since publication
Key Claims: – Good faith saves constitutional violations: This is the core critique of Leon expansion; supported by cases like Figueroa-Espinoza, Graham, and dozens of court rulings admitting unconstitutionally obtained surveillance evidence – Two-tiered constitutional protection: Analysis of how good faith creates asymmetry between early adopters of novel surveillance and later beneficiaries of constitutional clarity – Good faith slows constitutional development: Scholarly critique (Kamisar, LaFave, Kerr) arguing that good faith removes incentives for victims to appeal, preventing appellate review