Much of the procedure used in our judicial system has its origins in the common law of England. In English courts, the means by which evidence was found had little to do with whether a judge would admit it into the record. Common law provided (1) that the evidence might be used and (2) that there would be prosecution and punishment of anyone who broke the law to gain the evidence.
Until the eve of World War I, the U.S. Supreme Court used the old common law rule and permitted States and federal courts to admit evidence gained by an illegal search to convict an accused offender. In the late 19th century, as the U.S. system matured, many lawyers began to argue that the 4th Amendment to the Constitution—providing protection against "unreasonable searches and seizures"—was meaningless unless it was interpreted as a prohibition against the use of evidence gained illegally.
It could be said that the 4th Amendment had been dormant and devoid of practical application. It provided little protection except in spirit, until the Weeks case. This landmark decision by the Court became the first modern interpretation of the meaning of the Bill of Rights.
Weeks was arrested by a San Francisco policeman at his place of business. At the time of arrest, the officer conducted a search of Weeks's office without a warrant. The search revealed evidence about a suspected use of the U.S. mail to transmit lottery tickets, which was prohibited by federal law. The police then also searched Weeks's home, finding other papers that were irrelevant to the prosecution. Motivated by the results of the searches, the United States marshal, accompanied by local police and a federal postal inspector, returned to Weeks's home and searched his room in a third warrantless search, carrying away more letters and documents. Weeks filed suit to have the papers that were not relevant returned, and also petitioned to have the evidence excluded, or thrown out at the trial, because it was gained by an illegal search.
The case raised an essential 4th Amendment question: What protection does the 4th Amendment provide to a citizen? What use can be made of evidence gained by an illegal search? What penalty can be brought against officers who gain evidence by an illegal search? Was the evidence gained by an illegal search "tainted"? Should courts use the evidence but punish law enforcement officers by some means other than excluding the evidence?
For Weeks: The 4th Amendment is meaningless unless it provides some real protection. To state that people are safe from unreasonable searches and seizures has little value unless it is clear that evidence from such searches cannot be used in federal court. Federal officials should not be able to break the law in order to enforce the law.
For the United States: The Weeks prosecution proceeded logically: an arrest was made in connection with a search, and further searches produced further evidence of wrongdoing. At all times the officers were acting upon a growing body of evidence which suggested Weeks's involvement in illegal activity. He was guilty, he was in possession of evidence which was incriminating, and he should be punished.
Justice Day delivered the Court's unanimous decision to overturn Weeks's conviction. The Court declared illegally gained evidence "fruit of the poison tree" and ordered that illegally gained evidence be excluded in the future from any federal court.
Justice Day reasoned: "If letters and private documents can thus be seized and held and used as evidence against a citizen accused of an offence, the protection of the Fourth Amendment, declaring his right to be secure against such searches and seizures, is of no value, and…might as well be stricken from the Constitution." Drawing an important distinction between the ends and means of the criminal justice system, Day noted that the "efforts of the courts and their officials to bring the guilty to punishment, praiseworthy as they are, are not to be aided by the sacrifice of those great principles established by years of endeavor and suffering which have resulted in their embodiment in the fundamental law of the land.
"In holding them [papers] and permitting their use upon the trial, we think prejudicial error was committed…."
The Weeks ruling established that "evidence gained by an illegal search by a federal officer is inadmissible in federal courts." In cases where tainted evidence was essential to the conviction, the courts will order the release of a person who has been found guilty. Day wrote that the taking of papers by an official of the United States, "acting under the color of his office," was in violation of the constitutional rights of the defendant.
The Court's ruling in this case established what has become known as the Exclusionary Rule, barring the admission of evidence illegally obtained. The rule applied only to federal law enforcement and federal courts, however, and cooperation between federal officers and other law enforcement officers created so-called "silver platter" arrangements between one and the other. Until Elkins v. United States, 1960, federal officers would frequently tip off local officers, not bound by Weeks, who would then secure evidence by means not permitted under the Exclusionary Rule and transfer it to their federal colleagues "on a silver platter."
In defense of the Exclusionary Rule, Justice Louis B. Brandeis noted in 1928 that "Decency, security and liberty alike demand that government officials shall be subjected to the same rules of conduct that are commands to the citizen. In a government of laws, existence of the government will be imperiled if it fails to observe the law scrupulously. Our government is the potent, the omnipotent, teacher. For good or for ill it teaches the whole people by its example. Crime is contagious. If the government becomes a lawbreaker, it breeds contempt for the law; it invites every man to become a law unto himself, it invites anarchy."