In the United States v. Powell case of 1975, the Supreme Court ruled in favor of the government's broad authority to issue tax summons for investigative purposes. The Internal Revenue Service (IRS) had issued a summons to William Powell and his wife as part of an investigation into potential criminal violations regarding their income taxes. The Powells refused to comply with this summons, arguing that it was not issued in good faith because there was no legitimate purpose behind it and that it violated their Fifth Amendment rights against self-incrimination. However, the court held that a tax investigation could be conducted even if there is only suspicion about fraudulent activity without any specific charges being made yet. Furthermore, they stated that taxpayers cannot refuse such summonses on grounds of self-incrimination unless they can demonstrate how providing information would incriminate them specifically.

In the dissenting opinion for United States v. Powell, Justice Brennan disagreed with the majority's ruling that upheld a police officer's right to stop and frisk an individual based on reasonable suspicion of criminal activity without a warrant. He argued that this decision violated the Fourth Amendment rights of citizens against unreasonable searches and seizures. Brennan contended that such stops should only be permitted if there is probable cause to believe a crime has been committed, not merely on suspicion or hunches. The justice expressed concern about potential abuses of power by law enforcement officers who could use this broad interpretation as justification for racial profiling or other discriminatory practices. Furthermore, he believed it was inappropriate for courts to defer so heavily to police discretion in these matters rather than upholding constitutional protections.