Mo. Rev. Stat. § 386.480

No information furnished to the commission by a corporation, person or public utility, except such matters as are specifically required to be open to public inspection by the provisions of this chapter, or chapter 610, shall be open to public inspection or made public except on order of the commission, or by the commission or a commissioner in the course of a hearing or proceeding. The public counsel shall have full and complete access to public service commission files and records. Any officer or employee of the commission or the public counsel or any employee of the public counsel who, in violation of the provisions of this section, divulges any such information shall be guilty of a misdemeanor.