No member of the legislature shall be liable in any civil action, or criminal prosecution whatever, for words spoken in debate.

Article IV, §16 - ANNOT.

The sphere of legislative action protected under this section is broader than floor deliberations. A legislator may invoke the privilege under this section to immunize an aide from a subpoena to testify as to an investigation conducted by the aide at the legislator's request. State v. Beno, 116 Wis. 2d 122, 341 N.W.2d 668 (1984).

Not all activities of a legislator are protected by this section insofar as that activity is not an integral part of the deliberative and communicative processes. While legislative acts are protected by the speech and debate clause, political acts are not. Hiring, directing, and managing legislative caucus staff to oversee political campaigns is not protected. By its very nature, engaging in campaign activity is political. State v. Chvala, 2004 WI App 53, 271 Wis. 2d 115, 678 N.W.2d 880, 03-0442. See also State v. Jensen, 2004 WI App 89, 272 Wis. 2d 707, 684 N.W.2d 136, 03-0106.

This section provides only immunity from prosecution based on use of communications, and not secrecy for communications of government officials and employees. Legislative Technical Services Bureau Custodian of Records v. State 2004 WI 65, 272 Wis. 2d 208, 680 N.W.2d 792, 02-3063.

In a federal criminal prosecution against a state legislator there is no legislative privilege barring introduction of evidence of the legislator's legislative acts. United States v. Gillock, 445 U.S. 360 (1980).