In United States constitutional law

United States constitutional law

United States constitutional law is the body of law governing the interpretation and implementation of the United States Constitution.- Introduction :United States constitutional law defines the scope and application of the terms of the Constitution...

, the good-faith exemption (also good-faith doctrine) is a legal doctrine

Legal doctrine

A legal doctrine is a framework, set of rules, procedural steps, or test, often established through precedent in the common law, through which judgments can be determined in a given legal case. A doctrine comes about when a judge makes a ruling where a process is outlined and applied, and allows...

 providing an exemption to the exclusionary rule

Exclusionary rule

The exclusionary rule is a legal principle in the United States, under constitutional law, which holds that evidence collected or analyzed in violation of the defendant's constitutional rights is sometimes inadmissible for a criminal prosecution in a court of law...

.

The exemption allows evidence collected in violation of privacy rights as interpreted from the Fourth Amendment

Fourth Amendment to the United States Constitution

The Fourth Amendment to the United States Constitution is the part of the Bill of Rights which guards against unreasonable searches and seizures, along with requiring any warrant to be judicially sanctioned and supported by probable cause...

 to be admitted at trial

Trial (law)

In law, a trial is when parties to a dispute come together to present information in a tribunal, a formal setting with the authority to adjudicate claims or disputes. One form of tribunal is a court...

 if police officer

Police officer

A police officer is a warranted employee of a police force...

s acting in good faith

Good faith

In philosophy, the concept of Good faith—Latin bona fides “good faith”, bona fide “in good faith”—denotes sincere, honest intention or belief, regardless of the outcome of an action; the opposed concepts are bad faith, mala fides and perfidy...

 (bona fides) reliance upon a defective search warrant — that is, they had reason to believe their actions are legal (measured under the reasonable person

Reasonable person

The reasonable person is a legal fiction of the common law that represents an objective standard against which any individual's conduct can be measured...

 test).

The rule was established in the two companion case

Companion case

The term companion cases refers to a group of two or more cases which are consolidated by a appellate court while on appeal and are decided together because they concern one or more common legal issues...

s decided by the U.S. Supreme Court

Supreme Court of the United States

The Supreme Court of the United States is the highest court in the United States. It has ultimate appellate jurisdiction over all state and federal courts, and original jurisdiction over a small range of cases...

 in 1984: United States v. Leon

United States v. Leon

United States v. Leon, 468 U.S. 897 , was a search and seizure case in which the Supreme Court of the United States created the "good faith" exception to the exclusionary rule.-Background:...

(468 U.S. 902) and Massachusetts v. Sheppard (468 U.S. 981). The exception permits the courts to consider the mental state of the police officer.