The argument is meant to justify the continued demand for redacted grand-jury material from the now closed Special Counsel investigation into the Russian collusion investigation.
I have long supported the congressional demands for documents withheld by the Trump Administration as well as witnesses, including in my testimony during the House impeachment. The ability to acquire grand jury material turns on whether an impeachment is a "judicial proceeding" under Federal Rule of Criminal Procedure 6 (e). The district court and the court of appeals ruled that it does and that the House is entitled to the material. However, the House is arguing that this request is not moot after the acquittal of President Trump at the Senate impeachment trial.