The January 6th riot by supporters of former President Trump at the Capitol interrupted the presidential electoral count and was the worst attack on Congress in two centuries. In response, Congress formed the Select Committee to Investigate the January 6th Attack. However, legal challenges to the actions of the Select Committee represent the latest display of tensions relating to Congress’s powers of oversight, investigation, and its authority to issue and enforce subpoenas. Congress’s authority to investigate is broad, and the history of its investigations have established the power to compel testimony and the provision of documents, but these powers are not absolute and have often been the subject of controversy.