Mo. Rev. Stat. § 542.420: Evidence obtained in violation of law may not be used.

Whenever any wire communication has been intercepted, no part of the contents of such communication and no evidence derived therefrom may be received in evidence in any trial, hearing, or other proceeding in or before any court, grand jury, department, officer, agency, regulatory body, legislative committee, or other authority of the United States, a state, or a political subdivision thereof if the disclosure of that information would be in violation of sections 542.400 to 542.422.