Indiana constitution
Article 4: legislative
Section 8

Senators and Representatives, in all cases except treason, felony, and breach of the peace, shall be privileged from arrest, during the session of the General Assembly, and in going to and returning from the same; and shall not be subject to any civil process, during the session of the General Assembly, nor during the fifteen days next before the commencement thereof. For any speech or debate in either House, a member shall not be questioned in any other place.