A federal judge has mandated former Vice President Mike Pence to comply with a subpoena in the inquiry into former President Donald Trump's attempts to reverse the 2020 election results, according to a source knowledgeable about the decision.

Judge James Boasberg, the chief judge of the U.S. District Court for the District of Columbia, has required Pence to testify before the grand jury connected to the investigation led by special counsel Jack Smith.

The decision, issued on Monday, remains sealed as it pertains to grand jury matters. The order is a partial victory for Pence, who claimed that his constitutional role as part of the legislative branch protected him from having to testify about January 6th. Pence's team contended that the "speech or debate" clause of the Constitution, which can shield lawmakers from being forced to discuss legislative activity, granted him immunity from testifying.

However, Judge Boasberg ruled that while Pence does have some limited protections, the immunity does not prevent him from testifying about conversations related to Trump's alleged "illegality." Trump's legal team had also raised objections to Smith's subpoena based on executive privilege grounds, which Boasberg completely dismissed on Monday.

In November, Attorney General Merrick Garland appointed Smith to lead the investigation, and he issued a subpoena to Pence last month. Pence promised to fight the subpoena, stating, "no vice president has ever been subject to a subpoena to testify about the president with whom they served."

Pence has expressed his willingness to take the case to the Supreme Court if necessary and clarified that he was not asserting executive privilege over conversations unrelated to his January 6th duties.

It remains uncertain whether Pence will appeal Boasberg's ruling, and spokespeople for Pence and the Justice Department declined to comment on the decision. Pence stated in an interview with Newsmax's Greta Van Susteren that they are "evaluating the court's decision" and hinted at deciding on his 2024 plans in "the spring or early summer."

Boasberg's ruling on executive privilege is another triumph for the special counsel's team, which convinced another federal judge earlier this month that several former Trump administration officials must testify as well. Trump is expected to appeal the ruling, but it is unclear if he plans to appeal Boasberg's decision regarding Pence.

In reaction to the ruling, a Trump spokesperson stated, "The DOJ is continuously stepping far outside the standard norms in attempting to destroy the long-accepted, long-held, constitutionally based standards of attorney-client privilege and executive privilege."

The spokesperson further added, "There is no factual or legal basis or substance to any case against President Trump."