When Charles Katz was arrested in 1965, he was described by his attorney Harvey Schneider as "probably the preeminent college basketball handicapper in America." Katz’s case later led to a landmark Supreme Court ruling that reshaped Fourth Amendment protections against unreasonable searches and seizures.

In the 1967 decision United States v. Katz, the Supreme Court held that the Fourth Amendment applies when individuals have a "reasonable expectation of privacy," a standard that continues to influence rulings six decades later. This was evident on June 29, 2026, when the Court decided Chatrie v. United States, ruling that government-ordered analysis of cellphone location data constitutes a "search" under the Fourth Amendment.

Justice Elena Kagan, writing for the majority in Chatrie, stated, "An individual has a reasonable expectation of privacy in records about his cell phone's location, and police intrude on that constitutionally protected interest when they demand the information."

The Katz test replaced the earlier trespass doctrine, which focused on physical intrusion. Justice John Marshall Harlan II, in a concurring opinion in Katz, explained that the Fourth Amendment protects an "expectation of privacy" that "society is prepared to recognize as 'reasonable.'" The Court rejected the premise that warrantless wiretapping was permissible simply because there was no physical intrusion.

However, the Katz test has faced criticism. Some, including Justice Neil Gorsuch, argue that it "has no basis in the Constitution's text or history" and is difficult to apply because courts struggle to determine what constitutes a "reasonable" expectation of privacy.

Despite the new standard, it did not affect a sweeping exception to the Fourth Amendment announced over 40 years before Katz. For example, in the Court's 1999 ruling in Wyoming v. Carter, police did not violate a reasonable expectation of privacy when searching a car because the suspects were not "overnight social guests."

Historical cases also illustrate the complexities of privacy expectations. After discovering an unlicensed whiskey distillery in 1973, sheriff's deputies in Houston County, Georgia, connected the operation to Mitch Miller by reviewing his bank records obtained via grand jury subpoena rather than a warrant, highlighting the ongoing tension between privacy rights and law enforcement methods.

The Katz standard remains a pivotal yet contested element in Fourth Amendment jurisprudence, balancing individual privacy against government interests in an evolving technological landscape.

Sources