Jan. 6 Inquiry Weighs a Major Escalation: Subpoenaing Colleagues

In his statement later that day, Mr. McCarthy accused the committee of an abuse of power, complaining that it “wants to interview me about public statements that have been shared with the world, and private conversations not remotely related to the violence that unfolded at the Capitol.”

“I have nothing else to add,” he said.

It is extraordinarily rare for lawmakers to face subpoenas regarding their official activities, but the law raises no clear barrier to it, several legal specialists said.

The so-called speech or debate clause of the Constitution, intended to protect the independence of the legislative branch, says that senators and representatives “shall not be questioned in any other place” about any speech or debate in either chamber, and has been broadly interpreted to cover all legislative actions, not just words. On its face, however, that clause is limited to questioning them in “other” places, like courtrooms.

“The speech or debate clause deals with being questioned in another place, and the House is saying here that ‘the facts are within the control of one of our own, and we need him to share them with us,’” said Michael Davidson, a longtime former legal counsel of the Senate under majorities of both parties.

There is also precedent for the House to subpoena its own members in a narrow context. The House Ethics Committee, which is responsible for investigating allegations of misconduct by members, has authority under the chamber’s rules to subpoena members for testimony or documents, and members are required to comply.

The committee rarely discloses its work, so it is not clear how often it has issued such subpoenas; lawmakers facing ethics inquiries often either voluntarily cooperate or resign. Still, there is at least one public example of a lawmaker fighting a Senate Ethics Committee subpoena in court — and losing.

In 1993, Senator Bob Packwood, Republican of Oregon, was facing an investigation into allegations that he had sexually harassed numerous female staff members, and the ethics panel subpoenaed him to turn over certain pages of his personal diary. He balked, arguing that the request was too broad and violated his rights.