In Draper v. United States (1958), the Supreme Court ruled that an arrest and subsequent search without a warrant were valid under the Fourth Amendment, which protects against unreasonable searches and seizures. The case involved information from a paid informant who had previously provided accurate information to law enforcement officials. Based on this tip, officers arrested James Draper without a warrant for possession of heroin and subsequently found drugs during their search incident to his arrest. In its decision, the court held that if an officer has reasonable grounds to believe that someone is committing or has committed a crime based on credible evidence or reliable sources - such as in this case where they received detailed information about Draper's criminal activities from an informant with proven reliability - then it would be considered probable cause for arrest even without obtaining a warrant first.

In the dissenting opinion for Draper v. United States, Justice Douglas argued that the majority's decision undermined Fourth Amendment protections against unreasonable searches and seizures. He contended that an arrest without a warrant based on information from an informant was not reasonable unless there was independent corroboration of this information by law enforcement officers. In this case, he believed that such corroboration did not exist because the police only confirmed innocent details about Draper's behavior rather than any illegal activity before arresting him. Therefore, in his view, they lacked probable cause to make a lawful arrest or search him without a warrant under the Fourth Amendment standards established by previous Supreme Court decisions.