Here's more about the Minnesota Rules from Minnesota State Office of the Revisor of Statutes (on whose site you can find this slogan: "Our books are the official text of the law."):

"An administrative rule is a general statement adopted by an agency to make the law it enforces or administers more specific or to govern the agency's organization or procedure."

"An agency may adopt a rule only after the legislature has enacted a law granting this authority to the agency. An agency rule that is adopted under the rulemaking provisions of Minnesota Statutes, chapter 14, has the force and effect of law."