During the investigation, Mueller assembled a grand jury empowered to subpoena documents, require witnesses to testify under oath, and issue indictments for targets of criminal charges if probable cause was found.

[5][6] On July 26, 2019, the House Judiciary Committee filed an application with the United States Court of Appeals for the District of Columbia Circuit to release certain grand jury materials associated with Mulluer's investigation.

Circuit's panel of Judith W. Rogers, Thomas B. Griffith, and Neomi Rao ordered a briefing to address whether the House Judiciary Committee has Article III standing.

[8] On December 16, House General Counselor Douglas Letter filed a brief outlining the importance of obtaining the grand jury materials.

Circuit ordered the parties involved to file supplemental briefings by December 23, addressing whether articles of impeachment render the case moot and whether expedited consideration is still necessary.

The Supreme Court stayed the Circuit's mandate on May 8, 2020, and in June, the Justice Department filed a petition for a writ of certiorari which was opposed by the House Judiciary Committee.

[16][17] In late November 2020, the House requested that the Supreme Court postpone oral arguments until after the 117th United States Congress convenes and Joe Biden is inaugurated as president in January 2021, at which point the reconstituted Committee can determine if it still wishes to pursue the matter.