Me. Rev. Stat. tit. 5, § 8063-B

For every rule proposed by an agency, except for emergency rules, the agency shall file with the Secretary of State citations for up to 3 primary sources of information relied upon by the agency in developing the proposed rule. The agency shall include that information with a copy of the proposed rule when responding to a request under section 8053, subsection 3‑A. Professional judgment may be cited as one of those primary sources of information. Citations to primary sources of information are not subject to judicial review.