Federal judge Beryl Howell has dismissed former President Donald Trump's executive privilege claims and ordered Mark Meadows and other ex-aides to testify before a grand jury investigating Trump's efforts to overturn the election prior to the Jan. 6 attack on the U.S. Capitol, according to multiple sources close to the matter, according to ABC News.

Special counsel Jack Smith subpoenaed Trump's former chief of staff, Meadows, and other aides for testimony and documents related to the inquiry. Trump's legal team had contested the subpoenas by asserting executive privilege, which allows a president to keep communications with advisers confidential.

Judge Howell's sealed order last week dismissed Trump's executive privilege claims for Meadows and several others, including former Director of National Intelligence John Ratcliffe, former national security adviser Robert O'Brien, ex-top aide Stephen Miller, and former deputy chief of staff and social media director Dan Scavino. Sources revealed that former Trump aides Nick Luna and John McEntee, as well as ex-top DHS official Ken Cuccinelli, were also named in the order.

Trump is expected to appeal the ruling, according to sources briefed on the matter.

A Trump spokesperson criticized the Department of Justice (DOJ) in a statement, accusing them of "corrupting the legal process and weaponizing the justice system" by trying to undermine the attorney-client privilege and executive privilege.

Some of the aides ordered to testify had already appeared before the grand jury but did not answer certain questions related to their interactions with the former president, sources told ABC News. As a result, they would now be required to return for additional testimony.

Judge Howell previously dismissed Trump's executive privilege claim to block the testimony of Vice President Pence's top aides, Greg Jacob and Marc Short. The judge ruled that the current president, not a former president, has the authority to assert executive privilege, according to sources familiar with the proceedings.