Jordan said in the letter on Tuesday that the Justice Department changed its policies and procedures concerning criminal probes involving members of Congress and their staff, but has not provided clarification to date on its subpoenas to obtain private communications of certain congressional staff members.

"The Executive Branch used its immense law-enforcement authority to gather and search the private communications of multiple Legislative Branch employees who were conducting Constitutional oversight of the Department's investigative actions – actions that were later found to be unlawful," Jordan said, referring to an investigation into former President Donald Trump's campaign associate Carter Page.

Jordan explained that the requested information would help the Judiciary Committee articulate any potential legislative proposals on the issue, including those that would require the Justice Department to provide appropriate notice when it seeks to access private information belonging to an employee of Congress.