Muise testified on May 21, 2013, before the Subcommittee on National Security regarding the extent of radicalization in the American Muslim community and responses to it, highlighting threats from Islamism.

Darwish testified before the committee in 2011 on the threats of sharia law and radical Islam in the US, providing expert input on religious extremism.

Klayman testified before the committee in the late 1990s on Clinton administration misconduct, providing ammunition for Republican-led impeachment efforts.

Rebekah Mercer was subpoenaed by the U.S. House Committee on Oversight and Reform as part of its investigation into foreign interference in the 2016 election and the role of Cambridge Analytica.

The U.S. House Committee on Oversight and Accountability (formerly the U.S. House Committee on Oversight and Reform) has launched an investigation into Leonard Leo's dark money networks. In 2023, the committee subpoenaed Leo as part of this investigation, challenging him regarding his role in facilitating undisclosed payments to Ginni Thomas and the broader operations of his network. The probe focuses on potential violations of campaign finance laws and ethics rules, including potential conflicts of interest and ethical violations related to Leo's influence over judicial nominations and confirmations, as well as his financial ties to conservative activists and individuals connected to the judiciary. The committee has issued requests for documents and testimony regarding Leo's funding mechanisms, his role in managing funds for conservative causes, and his financial arrangements.

Following the unredaction of his name in Epstein-related documents, Wexner is scheduled to give sworn testimony (a deposition) before the House Oversight Committee to answer questions about his decades-long ties to Jeffrey Epstein.