Minn. Stat. § 14.06: REQUIRED RULES.

(a) Each agency shall adopt rules, in the form prescribed by the revisor of statutes, setting forth the nature and requirements of all formal and informal procedures related to the administration of official agency duties to the extent that those procedures directly affect the rights of or procedures available to the public.

(b) Upon the request of any person, and as soon as feasible and to the extent practicable, each agency shall adopt rules to supersede those principles of law or policy lawfully declared by the agency as the basis for its decisions in particular cases it intends to rely on as precedents in future cases. This paragraph does not apply to the Public Utilities Commission.