Pa. Const. art. II, § 11

Each House shall have power to determine the rules of its proceedings and punish its members or other persons for contempt or disorderly behavior in its presence, to enforce obedience to its process, to protect its members against violence or offers of bribes or private solicitation, and, with the concurrence of two-thirds, to expel a member, but not a second time for the same cause, and shall have all other powers necessary for the Legislature of a free State. A member expelled for corruption shall not thereafter be eligible to either House, and punishment for contempt or disorderly behavior shall not bar an indictment for the same offense.