The House select committee investigating the Jan. 6 attack on the Capitol voted Tuesday evening to hold Steve Bannon, a former aide to President Donald Trump , in contempt of Congress a move that could lead to federal criminal charges.

The vote was unanimous among the committees nine members.

When you think about what were investigating, a violent attack on the seat of our democracy its shocking to me, shocking that anyone would not do anything in their power to assist our investigation, committee chair Rep. Bennie Thompson (D-Miss.) said Tuesday. Its a shame that Mr. Bannon has put us in this position, but we wont take no for an answer.

Mr. Bannon will comply with our investigation, he later continued, or he will face the consequences.

Bannon has refused to comply with a subpoena issued by the committee last month demanding records of his communications with the Trump White House around the time of the attack. He also failed to appear for a hearing before the committee last Thursday.

The criminal referral will now go before the full House for a vote and, if approved, House Speaker Nancy Pelosi (D-Calif.) will formally send it to the U.S. attorney for Washington, D.C. Thompson reportedly expects the House to vote on the matter by Friday.

A contempt of Congress charge carries a maximum penalty of one year in prison and a fine of up to $100,000.

Rep. Liz Cheney (Wyo.), one of two Republicans on the committee, said Tuesday it appeared Bannon had substantial advance knowledge of the planning around the Jan. 6 attack, adding that there was no legal right to ignore the bodys subpoena. She later appealed to her GOP colleagues to support the committees mission, saying all of us who are elected officials must do our duty.

Pelosi introduced legislation this summer that created the nine-member select committee after Senate Republicans blocked the creation of an independent, bipartisan commission to investigate the Capitol riot, akin to the commission created to investigate the 9/11 attacks. The Jan. 6 committees official purpose is to investigate and report upon the facts, circumstances, and causes of the Capitol rioting and attempts to interfere with the peaceful transfer of power to President Joe Biden .

Bannon is just one of several individuals the committee has sought information from; it has also asked the National Archives for a wide swath of presidential records.

Through his attorney, Bannon claims that he has no right to respond to his subpoena because Trump is currently suing to prevent the committee from getting its hands on the documentation it seeks. The former president argues that executive privilege shields him from the committees prying eyes an argument that legal experts consider dubious.

Bannon has concluded that, until the matter of executive privilege is settled in court, his hands are tied.

The argument isnt especially strong, though its not entirely groundless, David Alexander Bateman, an associate professor of government at Cornell University who studies democracy, told HuffPost in an email.

Some legal experts have said Bannons claim is particularly weak due to the fact that he was not employed as a White House official over the period of time covered by the subpoena. He served in the Trump White House for just seven months, until August 2017.

Executive privilege is the concept that presidents have the right to keep secret some records such as communications if making them public could hurt the office of the presidency, even if they are in the public interest.

It is a hazy, vague, misunderstood, and ultimately malleable doctrine, asserted by presidents and acknowledged by the Court (basically for the first time in 1974 ) but whose implications or parameters have never been fully worked out. It is more of a political doctrine than a legal one, Bateman said.

Presidents tend to be very hesitant to chip away at executive privilege, in part because doing so could prevent presidential aides from giving frank advice. Yet Biden has already said he would not support Trumps claim to executive privilege with regard to the Jan. 6 committees demands.

These are unique and extraordinary circumstances, White House counsel Dana Remus said earlier this month in a letter explaining Bidens position.

The case would pit lawmakers specific needs for information against the former presidents more generalized interest in preserving confidential communications, Bateman said.

And since at issue here is whether the president sought to subvert the electoral process i.e., subvert the Constitution there is little plausible grounds by which the generalized interest in protecting confidentiality outweighs the specific interest in preventing future efforts to subvert the Constitution, he wrote.

It remains unclear how long the process of enforcing Bannons subpoena could take.

If the matter made its way up to the Supreme Court for review, the courts conservative majority could rule in Bannons favor.

Two of Trumps Supreme Court nominees Neil Gorsuch and Amy Coney Barrett have offered few clues as to how they might rule in an executive privilege case. Justice Brett Kavanaugh, the third Trump nominee, has offered mixed views on the topic.