United States v. Keehler 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, Keehler, was arrested for the possession of counterfeit money. The arresting officers had searched Keehler's home without a warrant and had seized the counterfeit money. At trial, the prosecution sought to introduce the counterfeit money as evidence against Keehler. The defendant argued that the evidence was obtained through an illegal search and seizure and should be excluded. The Supreme Court agreed with the defendant and held that the evidence was inadmissible. The Court reasoned that the Fourth Amendment of the United States Constitution protects citizens from unreasonable searches and seizures and that the evidence obtained in this case was obtained in violation of the Fourth Amendment. As a result, the Court held that the evidence was inadmissible and that the defendant could not be convicted.

In United States v. Keehler, the Supreme Court was tasked with determining whether a federal tax imposed on distilled spirits was constitutional. The majority opinion held that Congress had the power to impose such taxes under its authority to levy and collect taxes for revenue purposes. However, Justice Field dissented from this decision, arguing that Congress did not have the power to impose such a tax because it exceeded their enumerated powers granted by Article I of the Constitution. He argued that since there is no express grant of authority in Article I allowing for taxation of distilled spirits specifically, then any attempt by Congress to do so would be unconstitutional as it would amount to an exercise of legislative power beyond what has been delegated by the people through their representatives in government. Furthermore, he argued that if this type of taxation were allowed without limitation or restriction then it could lead down a slippery slope where all kinds of other forms of taxation could be imposed without proper authorization from either state legislatures or citizens themselves - something which he felt should never happen in our system based upon limited government and separation-of-powers principles established within our founding documents