The House’s top lawyer Monday urged a three-judge panel at the U.S. Court of Appeals for the D.C. Circuit to quickly issue a ruling on whether they’ll allow certain lawmakers to obtain grand jury materials redacted from the Mueller report, saying that information could show whether President Donald Trump was “untruthful” in his answers to then-special counsel Robert Mueller.

House general counsel Douglas Letter, arguing before Judges Neomi Rao, Thomas Griffith and Judith Rogers, said the grand jury information redacted from the Mueller report remains key to the House’s ongoing impeachment inquiry, as lawmakers hold hearings on allegations of improper withholding of military aid from Ukraine.