On Thursday, Senate Intelligence Committee Chairman Richard Burr told reporters that former National Security Adviser Michael Flynn would not be complying with a subpoena issued by the committee last Wednesday for documents pertaining to his interactions with Russian officials. Burr later walked back his assertion in a statement. “General Flynn’s attorneys have not yet indicated their intentions regarding the Senate Intelligence Committee’s subpoena,” he said. “Consistent with the Committee’s position since the beginning of or investigation, I welcome their willingness to cooperate.”

What would happen if Flynn really were to ignore the committee’s subpoena? That’s up to Senate leaders. Technically Congress has the authority to arrest witnesses and directly try them for contempt—that’s a dramatic step that hasn’t been taken since 1935. Instead the Senate could exercise one of two options: It could vote on a contempt referral to be passed on to the Justice Department for enforcement. Alternatively, it could bring the matter before a federal district court, which can then charge noncompliant witnesses with contempt of court. Congressional Republicans did the former during the Obama administration when then–Attorney General Eric Holder and the IRS’s Lois Lerner refused to comply with issued subpoenas. Both times, the Justice Department simply refused to prosecute the cases. Susan Hennessey and Helen Klein Murillo of Lawfare write that the Flynn case introduces a few wrinkles to the process given Robert Muller’s appointment as special counsel—a position that may or may not be the appropriate destination for a contempt referral—as well as Flynn’s status as an ex-official:

Typically, certifications against sitting executive branch officials have been made to the U.S. Attorney for the District of Columbia […] Flynn, however, is not a current official and, recent federal grand jury subpoenas to Flynn’s associates were issued by the Eastern District of Virginia. So it’s unclear precisely where a referral would go. It is also unclear whether, given the subject matter, there is any reason the Senate could not determine that Mueller is the appropriate U.S. Attorney for the matter. If the certification were issued to the U.S. Attorney for D.C. or EDVA (or any other district, for that matter), the relevant offices would report to Rosenstein, and not Attorney General Sessions who is [recused], in deciding whether or not to refuse to bring the matter to the grand jury. Even in that case, Rosenstein may well defer the issue to Mueller, since the production of documents bear on his investigative equities.

The district court route would entail the Senate passing a resolution authorizing civil action that could lead to Flynn being charged with contempt of court. “If the court orders compliance with the subpoena and the witness refuses, they are then subject to contempt of court and imprisonment,” Hennessy and Murillo write. The House did this anticipating the Justice Department’s refusal to prosecute Holder in 2012, only to have a federal judge turn them down as well.