WASHINGTON — A federal judge has ordered former Vice President Mike Pence to comply with a subpoena in the investigation into former President Donald Trump’s efforts to overturn the 2020 election results, according to a source familiar with the decision.

The ruling from Judge James Boasberg, the chief judge for the U.S. District Court for the District of Columbia, requires Pence to testify before the grand jury tied to the probe led by special counsel Jack Smith.

Pence’s team argued that the “speech or debate clause” of the Constitution, which can protect lawmakers from being compelled to discuss legislative activity, granted him immunity from testifying about his role certifying the election results as president of the Senate on Jan. 6. Boasberg ruled that while Pence does have some limited protections because of that, the immunity does not prevent him from testifying about conversations related to alleged “illegality” on Trump’s part, the judge ruled.

The ruling, which remains under seal because it involves grand jury matters, gave Pence a partial victory regarding his argument that he was shielded from having to testify about Jan. 6 because of his constitutional role as part of the legislative branch.

Smith, whom Attorney General Merrick Garland appointed to lead the investigation in November, issued the subpoena in February, and Pence vowed to fight it, saying “no vice president has ever been subject to a subpoena to testify about the president with whom they served.”

It’s unclear whether Pence plans to appeal Boasberg’s decision. Pence previously said he would take the case to the Supreme Court if necessary. He told ABC News he wasn’t asserting executive privilege over conversations unrelated to his duties on Jan. 6.

Spokespeople for Pence and the Department of Justice declined to comment on the judge’s decision.

Trump’s legal team had separately made wholesale objections to Smith’s subpoena on executive privilege grounds — claims which Boasberg also completely rejected Monday.

Boasberg’s ruling on executive privilege marks another victory for the special counsel’s team, which persuaded another federal judge earlier this month that a number of Trump’s former administration officials — including Dan Scavino, Stephen Miller, Robert O’Brien, John Ratcliffe, Ken Cuccinelli, and John McEntee — must also testify. Trump is expected to appeal that ruling. It was not immediately clear whether he plans to appeal Boasberg’s decision on Pence as well.