Steve Bannon is stonewalling the House committee investigating the January attack on the U.S. Capitol, indicating that he would not comply with a subpoena for documents or testimony related to their inquiry.

Bannon’s lawyer, Robert Costello, sent a letter to the committee on Friday explaining that former president Donald Trump has asked Bannon and others to invoke executive privilege.

“We must accept his direction and honor his invocation of executive privilege,” Costello wrote. “As such, until these issues are resolved, we are unable to respond to your request for documents and testimony.”

It is illegal to defy a congressional subpoena. Rep. Jamie Raskin (D-MD) says the committee will pursue “the full panoply of enforcement sanctions available to us” including “criminal contempt citations, civil contempt citations and the use of Congress’s own inherent contempt powers.”

CNN reports that Bannon’s invocation of executive privilege is questionable:

Privilege claims normally apply to close officials around the president and deliberations between government employees, and Bannon was fired from his role as a White House adviser in 2017.

Many legal experts say Bannon, as a private citizen, would have no standing to block a subpoena by claiming executive privilege.

Bannon was among four Trump associates to be subpoenaed by the committee. They were all asked to hand over documents by the end of this week. Trump’s former chief of staff, Mark Meadows “has also responded to the special committee” according to CNN, “although a source would not characterize Meadows’ response.”

It is unclear how the other subpoenaed officials – Kash Patel, a former defense department aide, and Dan Scavino, a former Trump staffer – have responded.

POLITICO explains:

If any of the foursome don’t comply, the committee could seek criminal contempt referrals, which would require the House to take a full floor vote when it returns to session later this month. That move, if taken, would send the matter to the Justice Department for review. It’s unclear whether DOJ would act quickly on any prospective referrals, but members of the Jan. 6 panel have expressed hope that the Biden administration would act urgently.

CNN reports on why the committee wants to talk to Bannon in particular:

Bannon, who was Trump’s former White House chief strategist, spoke with Trump in December, urging him to focus on January 6 — the date of the official certification on the Electoral College vote by Congress, according to authors Bob Woodward and Robert Costa in their book “Peril.” “‘We’re going to bury Biden on January 6th,'” Bannon is quoted as saying.

Woodward and Costa also reported that Trump called Bannon following his contentious January 5 meeting with then-Vice President Mike Pence, in which the vice president said he does not have the authority to block certification of Joe Biden’s win.

In its letter to Bannon, the select committee cited communications he had with Trump in December “and potentially other occasions” in which Bannon reportedly urged Trump “to plan for and focus his efforts on January 6.”