Thanks, I definitely didn’t remember this, but reviewing it in the era we’re about to enter is pretty depressing:

https://constitution.congress.gov/browse/essay/artI-S6-C1-3-1/ALDE_00013300/

…They shall in all Cases, except Treason, Felony and Breach of the Peace, be privileged from Arrest during their Attendance at the Session of their respective Houses, and in going to and returning from the same; and for any Speech or Debate in either House, they shall not be questioned in any other Place.

As succinctly described by the Court, the Clause’s immunity from liability applies even though their conduct, if performed in other than legislative contexts, would in itself be unconstitutional or otherwise contrary to criminal or civil statutes. This general immunity principle forms the core of the protections afforded by the Clause.

Once it is determined that the Clause applies to a given action, the resulting protections from liability are absolute, and the action may not be made the basis for a civil or criminal judgment against a Member. In such a situation, the Clause acts as a jurisdictional bar to the legal claim

Basically, I assume GOP congressional members are going to be Trump’s attack dogs like we’ve never seen, since they can threaten outright criminal conduct without repercussion.