The good faith exception from United States v. Leon, 468 U.S. 897 (1984), allows prosecutors to use evidence seized under a defective search warrant when the officers who executed it reasonably believed the warrant was valid. The Supreme Court ruled 6–3 that the Fourth Amendment’s exclusionary rule exists to deter police misconduct, so suppressing evidence gathered by officers who followed the rules and relied on a judge’s signature serves no useful purpose.1Justia. United States v Leon, 468 US 897 (1984)
What the Court Actually Held
Justice Byron White wrote the majority opinion, joined by Chief Justice Burger and Justices Blackmun, Powell, Rehnquist, and O’Connor. The holding: evidence obtained by officers acting in objectively reasonable reliance on a search warrant issued by a neutral judge is admissible, even if the warrant later turns out to be invalid for lack of probable cause.2Cornell Law Institute. United States v Leon
The reasoning turned on the purpose of the exclusionary rule. The rule exists to change police behavior. When an officer prepares an affidavit, submits it to a judge, receives a warrant, and executes the search within its terms, that officer has already done what the law asks. Throwing out the resulting evidence because the judge later got the probable cause analysis wrong does not deter future misconduct by that officer or anyone else. It simply costs the prosecution reliable evidence.
The case itself came out of a Burbank, California drug investigation. A detective’s affidavit relied on a tip from a confidential informant, a state judge signed the warrant, and officers seized large quantities of drugs. The trial court and Ninth Circuit both found the affidavit fell short of probable cause and suppressed the evidence, acknowledging the detective had acted in good faith but refusing to recognize any exception on that basis.1Justia. United States v Leon, 468 US 897 (1984) The Supreme Court reversed and created the exception the lower courts had refused to apply.
When the Good Faith Exception Does Not Apply
The exception is not a blank check. The majority identified four situations where evidence remains subject to suppression despite the existence of a signed warrant:
- The officer misled the judge by including information in the affidavit that the officer knew was false, or showed reckless disregard for the truth.1Justia. United States v Leon, 468 US 897 (1984)
- The issuing judge abandoned the neutral, detached role and functioned as a rubber stamp for law enforcement.
- The affidavit was so lacking in probable cause that no reasonable, well-trained officer could have believed it was adequate.3Office of Justice Programs. Judicial Preference for the Search Warrant – The Good Faith Warrant Exception to the Exclusionary Rule
- The warrant itself was defective on its face, failing to describe the place to be searched or the items to be seized with the specificity the Fourth Amendment requires.4Constitution Annotated. Amdt4.5.1 Overview of Warrant Requirement
The third category is where most defense challenges live. A signed warrant does not immunize an affidavit that reads more like a hunch than a factual case for probable cause. If the paperwork was plainly inadequate, a trained officer should have recognized it, and reliance on the judge’s signature stops being reasonable.
Challenging a False Affidavit Through a Franks Hearing
The first situation connects to a procedure the Court established in Franks v. Delaware, 438 U.S. 154 (1978). A defendant who can make a substantial preliminary showing that the affiant knowingly or recklessly included false statements in the warrant application is entitled to an evidentiary hearing.5Justia U.S. Supreme Court Center. Franks v Delaware, 438 US 154 (1978) The challenge has to be specific. Vague accusations will not do. The defendant must identify the false statements, explain why they were false, and back the claim with proof such as sworn affidavits or witness statements.
If the defendant meets that threshold, the court sets aside the false material and asks whether what remains still supports probable cause. If it does, the warrant stands. If it does not, the warrant is voided and the evidence is suppressed. The Franks procedure targets deliberate or reckless falsehoods by the officer who signed the affidavit. Honest mistakes and inaccuracies traceable to an informant, standing alone, do not open the door to a hearing.6Office of Justice Programs. Misstatements in Affidavits for Warrants – Franks and Its Progeny
The Dissent’s Warning
Justices Brennan, Marshall, and Stevens dissented. Brennan wrote the primary opinion, and his critique remains one of the more forceful attacks on the majority’s reasoning in modern Fourth Amendment law.
Brennan argued that the majority mischaracterized the exclusionary rule as a “judicially created remedy” separable from the Fourth Amendment. In his view, the rule is a constitutional requirement built into the amendment itself: if the government can freely use illegally seized evidence, the amendment’s protection is hollow.1Justia. United States v Leon, 468 US 897 (1984)
He also attacked the deterrence framing. The majority asked whether suppression would change the behavior of the individual officer in the case at hand. Brennan said that was the wrong question. The exclusionary rule works by promoting institutional compliance across entire law enforcement agencies, not by adjusting one officer’s conduct on one occasion. Telling officers a judge’s signature is enough, he argued, would discourage careful review of warrant applications at both the police and judicial levels.
Brennan predicted the exception would expand over time. He cited a 1979 General Accounting Office study finding that only 0.4% of federal cases declined for prosecution were dropped primarily because of search and seizure problems, pushing back on the majority’s premise that suppression was a serious drag on law enforcement.
How the Exception Has Grown Since 1984
Brennan’s expansion prediction turned out to be right. The Supreme Court has repeatedly extended the same deterrence-focused reasoning well past defective warrants.
In Arizona v. Evans, 514 U.S. 1 (1995), an officer arrested a driver based on a computer entry showing an outstanding warrant. The warrant had been quashed seventeen days earlier, but the court clerk had never updated the records. A search incident to the arrest turned up marijuana. The Court refused to suppress the evidence because the error was made by a court clerk, and the exclusionary rule targets police misconduct.7Cornell Law Institute. Arizona v Evans, 514 US 1 (1995)
Herring v. United States (2009) pushed the reasoning further. This time the recordkeeping error came from another police department, not a court. An officer arrested a suspect based on a neighboring county’s report of an active warrant that had actually been recalled months earlier, and a search turned up drugs and a gun. The Court held that isolated negligence by police, as opposed to systemic problems or reckless disregard for constitutional requirements, does not trigger the exclusionary rule. Police conduct has to be sufficiently deliberate that exclusion can meaningfully deter it, and sufficiently culpable that the deterrence is worth the cost.
Davis v. United States (2011) extended the exception to officers who conducted searches in objectively reasonable reliance on binding appellate precedent that was later overruled. If a court of appeals says a certain kind of search is legal, officers who followed that ruling do not lose their evidence when the Supreme Court later changes the law.
Heien v. North Carolina (2014) went further still. An officer stopped a car for having one working brake light, honestly believing state law required two. The statute was ambiguous, and the Court held that an officer’s objectively reasonable mistake about what the law requires can supply the reasonable suspicion needed for a lawful traffic stop.
State Constitutions Can Provide More Protection
Leon interprets the federal Constitution and binds every court on the question of what the Fourth Amendment requires. States can offer more protection under their own constitutions, and several state supreme courts have declined to adopt the good faith exception as a matter of state constitutional law. In those states, evidence seized under a defective warrant may still be suppressed in state prosecutions even when it would survive under Leon. Anyone assessing a suppression argument needs to check the state’s rule as well as the federal one.
What Leon Means for a Suppression Challenge Today
Showing that a warrant lacked probable cause is no longer enough to get evidence thrown out in federal court. The prosecution will invoke the good faith exception, and the burden shifts to the defense to bring the case within one of the four Leon limitations or a Franks challenge to the affidavit. The strongest lanes are usually the affidavit-was-plainly-inadequate argument and, when the facts support it, a specific, documented showing that the affiant lied or acted with reckless disregard for the truth. Everything about the challenge has to be built around Leon’s framework rather than around probable cause alone.