United States v. Hoffman 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 presented at trial was obtained through an illegal search and seizure. The Court held that the evidence was inadmissible and that the defendant could not be convicted. The case arose when the defendant, Hoffman, was arrested for selling liquor without a license. The arresting officers had searched Hoffman's home without a warrant and seized the liquor. Hoffman argued that the search and seizure were illegal and that the evidence should not be used against him. The Supreme Court agreed, ruling that the evidence was inadmissible and that Hoffman could not be convicted. The Court held that the Fourth Amendment of the United States Constitution protects citizens from unreasonable searches and seizures. The Court reasoned that the search and seizure of Hoffman's home was unreasonable and violated his Fourth Amendment rights. Therefore, the evidence obtained from the search and seizure was inadmissible and Hoffman could not be convicted. This case established the principle that evidence obtained through an illegal search and seizure is inadmissible in court and cannot be used to convict a defendant. This principle is still in effect today and is known as the "exclusionary rule."

In United States v. Hoffman, the Supreme Court was tasked with determining whether a federal court had jurisdiction to try an individual for violating a state law. The majority opinion held that it did not have such authority and dismissed the case. However, Justice Field dissented from this ruling, arguing that Congress has broad powers under the Constitution to regulate commerce between states and foreign nations as well as among Indian tribes. He further argued that Congress could use these powers to punish violations of state laws when they interfere with interstate or international commerce or involve fraud against Indians living on reservations within a particular state's borders. As such, he concluded that federal courts do indeed possess jurisdiction in cases involving violations of state laws which affect interstate or international trade or involve fraud against Native Americans living on reservations within those states' boundaries.