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48 U.S. Code § 1423c - Privileges of members

The members of the legislature shall, in all cases except treason, felony, or breach of the peace, be privileged from arrest during their attendance at the legislature and in going to and returning from the same.
No member of the legislature shall be held to answer before any tribunal other than the legislature itself for any speech or debate in the legislature.
(Aug. 1, 1950, ch. 512, § 13, 64 Stat. 388.)