In the 1917 case of Weeks v. United States, the U.S. Supreme Court established what is now known as the "exclusionary rule." The case involved Fremont Weeks who was arrested at his place of work by federal officers without a warrant and had his home searched while he was in custody, again without a warrant. During these searches, evidence incriminating him for transporting lottery tickets through mail was seized and used to convict him. On appeal to the Supreme Court, it ruled that this violated Week's Fourth Amendment rights against unreasonable search and seizure since no warrants were obtained prior to conducting them. As such, any evidence gathered from these illegal searches could not be used in court - hence establishing the exclusionary rule which remains an important part of American jurisprudence today.

In the dissenting opinion for Weeks v. United States, Justice McKenna argued that the majority's decision to exclude evidence obtained through an illegal search and seizure was too broad of a ruling. He contended that while it is important to protect individual rights against unlawful intrusion by government officials, there should be some consideration given to the necessity of such actions in certain circumstances. In his view, if evidence relevant to a crime is discovered during an illegal search or seizure, it should not automatically be excluded from trial proceedings as this could potentially hinder law enforcement efforts and obstruct justice. Instead, he suggested that each case should be evaluated individually based on its specific facts and circumstances before deciding whether or not illegally obtained evidence can be used in court.