The Justice Department revealed in a court filing Sunday that former Special Counsel Robert Mueller did not make either Donald Trump Jr. or former White House Counsel Don McGahn testify before a grand jury he used for his Russia investigation. The filing was in response to U.S. District Judge Beryl Howell's ruling Thursday that the Justice Department was withholding too much information from the House Judiciary Committee in its ongoing wrangling with Attorney General William Barr over Mueller's evidence.

DOJ reveals in court doc now, per court order: Donald McGahn and Donald Trump Jr. did not testify before Mueller grand jury https://t.co/CKMRoGGRXw pic.twitter.com/eycZv5ROHA — Mike Scarcella (@MikeScarcella) October 20, 2019

Howell appeared perplexed by Mueller's decision. "The Special Counsel's reasons remain unknown," she wrote in her opinion. "The reason is not that the individuals were insignificant to the investigation. To the contrary, both of the non-testifying individuals named in paragraph four figured in key events examined in the Mueller Report."

McGahn's lawyer offered one explanation, telling Politico that because McGahn "voluntarily agreed to be interviewed" for about 30 hours at Mueller's office, "there was no need for a grand jury subpoena." Former federal prosecutor Renato Mariotti found that explanation plausible. "If a witness agrees to be interviewed by FBI agents, as McGahn did, typically prosecutors won't put him in the grand jury to testify unless there's a concern that he will later change his story," he tweeted. "As for Trump Jr., this suggests to me that his lawyers said he would take the Fifth."

Lawyers for some of Mueller's other witnesses have said they believe Trump Jr. told Mueller's prosecutors he would assert his Fifth Amendment right against self-incrimination before the grand jury, and Mueller's team decided not to compel his testimony with a promise of immunity, Politico reports. Howell also noted in her ruling last week that Mueller declined to subpoena President Trump for an interview or grand jury testimony despite being dissatisfied with the president's written responses to his prosecutors' questions.

The upshot of Sunday's filing is that is strengthens the House Judiciary Committee's case "that Barr redacted the Mueller [Report] itself improperly," journalist Marcy Wheeler argues, because it hides the "non-testimony" of Trump and his son "behind frivolous redactions." Peter Weber