My understanding is that when they are not in session, or in the process of going to session, they have no Constitutional protections. So if Congress is adjourned, it's open season. If they get arrested and imprisoned during this time, it seems their seat will simply be vacant until they resign, the House ejects them from membership, or the state takes any constitutional actions it may have under the laws of the state to do something. Would like to hear any actual examples of this happening, and how it was resolved.