In 1922, the United States Senate launched an investigation into what would become the most infamous story of executive-branch corruption in American history until Watergate. Teapot Dome, as the scandal came to be known, involved secret deals given out by Warren Harding’s administration for access to oil reserves in Wyoming and California. Not one but two special prosecutors were appointed to investigate alongside Congress.
The scandal led, among other things, to the laws governing tax disclosures that have allowed the present Congress to press—so far unsuccessfully—for access to President Donald Trump’s tax returns. It also established Congress’s power to investigate more generally. When senators grew suspicious of Attorney General Harry Daugherty’s failure to prosecute the Cabinet officials and oil executives at the center of the scandal, they demanded testimony from witnesses in order to obtain what they described as “information necessary as a basis for such legislative and other action as the Senate may deem necessary and proper.”
The battle escalated to the Supreme Court, which found that the Senate had been within its rights to issue subpoenas even though the Constitution granted no explicit investigatory power to Congress. Witness testimony, the Court wrote, would help the Senate determine whether the Justice Department had been properly governed and whether action by Congress was necessary to prevent mismanagement in the future. As the justices put it, “The power of inquiry … is an essential and appropriate auxiliary to the legislative function.”