In Sibron v. New York (1967), the U.S Supreme Court ruled that a police officer's search of Peter Sibron, which led to his arrest for heroin possession, was unconstitutional because it violated the Fourth Amendment protection against unreasonable searches and seizures. The court held that an officer must have specific evidence or reasonable suspicion of criminal activity before conducting such a search. In this case, an officer had observed Sibron talking with several known drug addicts over eight hours but did not see any crimes being committed. Based on these observations alone, he approached Sibron in a restaurant and searched him without consent or warrant - finding heroin in his pocket leading to his arrest and conviction under New York law. However, the Supreme Court overturned this conviction stating that mere association with criminals does not provide enough grounds for a search without either consent or warrant.

In the dissenting opinion for Sibron v. New York, Justice Harlan argued that the majority's decision to invalidate a search and seizure under Section 180-a of the New York Code of Criminal Procedure was misguided. He contended that this ruling would undermine police authority and hinder their ability to perform necessary duties in maintaining public safety. According to him, it is not unreasonable for an officer who has reasonable suspicion about criminal activity to conduct a limited search for weapons as a self-protective measure. The justice also criticized the majority's interpretation of "reasonable cause" as being too narrow and restrictive, arguing instead that it should be understood within its broader context which includes considerations such as officer safety and crime prevention.