Mo. Rev. Stat. § 8.966

The purpose of sections 8.964 to 8.974 is to fulfill the state's proprietary objectives in maintaining and promoting the economical, nondiscriminatory, and efficient expenditures of public funds in connection with publicly funded or assisted construction projects. Nothing in sections 8.964 to 8.974 shall prohibit employers or other parties covered by the National Labor Relations Act from entering into agreements or engaging in any other activity arguably protected by law, nor shall any aspect of sections 8.964 to 8.974 be interpreted in such a way as to interfere with the labor relations of parties covered by the National Labor Relations Act.