In the 1975 case Dillingham v. United States, the Supreme Court examined whether a warrantless search of an automobile was justified under the Fourth Amendment's "automobile exception." The defendant, Dillingham, had been convicted for possessing stolen mail after police officers conducted a warrantless search of his vehicle and found stolen checks inside. He appealed on grounds that this violated his constitutional rights against unreasonable searches and seizures. However, the court upheld his conviction by affirming that automobiles are subject to different standards than homes or offices due to their inherent mobility which often makes obtaining a judicial warrant impractical in time-sensitive situations. This ruling reinforced previous decisions establishing what is known as the "automobile exception" to the Fourth Amendment’s requirement for warrants before conducting searches.

In the dissenting opinion for Dillingham v. United States, it was argued that the majority's decision to uphold a conviction based on evidence obtained through warrantless electronic surveillance violated Fourth Amendment protections against unreasonable searches and seizures. The dissent emphasized that such surveillance constitutes an invasion of privacy and should be subject to strict judicial oversight. It also pointed out inconsistencies in how the Court had previously interpreted similar cases involving wiretapping or eavesdropping devices, suggesting a need for clearer guidelines regarding when such methods can be used without infringing upon constitutional rights. Furthermore, it expressed concern about potential abuses of power if law enforcement agencies are allowed to conduct covert operations without obtaining warrants first.