The Fourth Amendment guarantees "the right of the people to be secure in their persons, houses, papers, and effects, against unreasonable searches and seizures." The Founding Fathers of the constitution knew all too well how the king's soldiers and marshals had abused their power through sweeping searches of American homes before 1776 thus resulting in the creation of the Fourth Amendment. Despite the establishment of the Fourth Amendment, many years existed in which state and federal governments admitted evidence obtained through "unreasonable" search and seizures in criminal trials. The only criteria used by the judge were whether the evidence was incriminating and if it would assist in convicting the defendant. Through the years, the Supreme Court interpretation of the Fourth Amendment has changed due to the development of search and seizure law. .
The definition of "unreasonable" was first dealt with at the federal level in the 1914 case of Weeks v. United States. Federal law enforcement authorities accused the defendant, Freemont Weeks of using the mail for illegal purposes. After his arrest, the home in which Weeks was staying was searched without a valid search warrant. Evidence in the form of letters were found in his room and admitted in the trial. Weeks was then convicted of the federal offence based on incriminating evidence. The Supreme Court argued that evidence gathered in an illegal manner, without probable cause or without a search warrant, should be excluded from criminal trials. The exclusionary rule was adopted to prevent abuses by the police and other government officials. The logic followed that if police understand that evidence seized in a manner that violates any of the provisions of the Fourth Amendment will be excluded from court proceedings, they will less likely conduct searches without warrants or without probable cause. The Weeks decision only affected federal courts, and two-thirds of the state courts rejected the exclusionary rule, claiming the rule placed unnecessary burdens on the police and the rule favored the guilty.
