Hart v. United States was a United States Supreme Court case that dealt with the issue of whether a defendant could be convicted of a crime if the evidence used to convict them was obtained through an illegal search and seizure. The case involved a man named Hart who was convicted of selling liquor without a license. The evidence used to convict him was obtained through a search of his home without a warrant. The Supreme Court ruled in favor of Hart, finding that the evidence used to convict him was obtained illegally and could not be used in court. The Court held that the Fourth Amendment of the United States Constitution protects citizens from unreasonable searches and seizures and that any evidence obtained through an illegal search and seizure is inadmissible in court. This ruling established the exclusionary rule, which states that any evidence obtained through an illegal search and seizure is inadmissible in court. The Hart v. United States case is an important Supreme Court case that established the exclusionary rule and has been used in many subsequent cases to protect citizens from unreasonable searches and seizures. The ruling has been used to protect citizens from the government's overreach and to ensure that their rights are respected.

Justice Field delivered the dissenting opinion in Hart v. United States, arguing that Congress had no authority to pass a law which allowed for the seizure of property without due process of law. He argued that such an act violated both the Fifth Amendment and Article I, Section 8 of the Constitution, which states that Congress has only limited powers granted by the people. Furthermore, he noted that this was not a case where there was any evidence or proof presented to show why it would be necessary to take away someone's property without due process; rather it seemed like an arbitrary decision made by Congress with no legal basis or justification. In conclusion Justice Field stated his belief that if such laws were allowed then citizens could have their rights taken away from them at any time without being given proper notice or opportunity to defend themselves against these actions.