514 U.S. 927 (1995), argued 28 Mar. 1995, decided 22 May 1995 by vote of 9 to 0; Thomas for the Court. Throughout the 1980s and 1990s the so-called war on drugs posed an increasing number of new constitutional issues. From the perspective of law enforcement agencies, the “war” required the fullest possible exertion of their authority; from the vantage point of civil libertarians, the rights of suspects were likely to be the first casualties of the war. One area of particular importance was the extent to which the police might break into a residence without announcing themselves. English common law provided for the “knock-and-announce” rule, which required the sheriff to announce his presence before entering a premises. The Supreme Court in Ker v. California (1963) issued a split decision on the matter, although many states and the federal government subsequently acted in response to it by requiring police to announce themselves. However, prosecutors in many of these same states had responded to the rising tide of drug-related crimes by attempting to carve out exceptions when there was a likelihood that the delay caused by the announcement would result in the destruction of evidence.
Arkansas was one of a handful of states that had no knock-and-announce statute. Hence, on New Year's Eve 1992 the Arkansas State Police burst unannounced into the home of Sharlene Wilson of Malvern, Arkansas. Through an informant, the police had made a number of narcotics purchases from Wilson in the days before the raid. Without knocking, the police entered Wilson's home and found a large quantity of narcotics, a gun, and ammunition and discovered Wilson busily flushing drugs down the toilet. She was arrested and ultimately sentenced to thirty one years in jail. She appealed to the Arkansas Supreme Court, claiming that the search warrant was invalid because the police had failed to follow the common-law rule of knock and announce, a rule that Wilson claimed was enshrined in the Fourth Amendment to the federal Constitution. The Arkansas Supreme Court rejected this argument and concluded that the Fourth Amendment did not include the knock-and-announce principle. The United States Supreme Court agreed to hear the case because of the conflicting views held among the lower federal courts on the subject of whether the Fourth Amendment did include the common-law rule.
Justice Clarence Thomas overturned the state court ruling and remanded the case back to the Arkansas courts for a determination of the facts. Most significantly, however, Thomas found that the Fourth Amendment's protection against unreasonable searches and seizures included the common-law principle of knock and announce. Thomas relied on a reading of the history of the Fourth Amendment to reach his conclusion, but he also found that the framers of the amendment never intended that the police must always knock and announce themselves before entering. Far from mandating a rigid rule, Thomas held, the framers wanted to make certain that the police had sufficient discretion to prevent evidence from being destroyed, police officers from being put in harm's way, and suspects from escaping. The question of how to apply this discretion was left by the high court to lower courts to decide on a factual basis.