In the United States v. Powell et al., 1964, the Supreme Court ruled in favor of the Internal Revenue Service (IRS), affirming its authority to summon and examine records from taxpayers under investigation without having probable cause for criminal prosecution. The case arose when William J. Powell and his wife refused to comply with an IRS summons demanding access to their books, records, and other documents related to tax liability assessment for certain years. They argued that this was a violation of their Fourth Amendment rights against unreasonable searches and seizures as there was no probable cause shown by the IRS. However, Justice Byron White delivered the unanimous decision stating that such a requirement would unduly hinder tax investigations since they are primarily civil proceedings rather than criminal ones; thus not requiring probable cause like in traditional law enforcement cases.

In the dissenting opinion for United States v. Powell, Justice William O. Douglas argued that the Internal Revenue Service (IRS) should not have unlimited power to summon a taxpayer's records without any specific reason or cause. He believed this was an invasion of privacy and violated Fourth Amendment rights against unreasonable searches and seizures. Douglas contended that such broad powers could lead to abuse by government officials, potentially using their authority for harassment or intimidation rather than legitimate investigative purposes. He also expressed concern about the potential chilling effect on citizens' willingness to keep accurate financial records if they knew these could be arbitrarily demanded by tax authorities at any time without justification.