The Mackinac Center’s brief urges the Michigan Supreme Court to hold that the judiciary need not defer to administrative agencies’ interpretations of ambiguous statutes. Alternatively, because Michigan courts (unlike federal courts) have not determined that agency rules created through formal adjudication are equivalent to rules created through notice-and-comment rulemaking, the Court could hold simply that there is no judicial deference to rules created through adjudication, leaving aside the question of deference to notice-and-comment rules.
The Michigan Supreme Court decided the case in July 2008. The justices held that the rulings of state agencies should not receive deference from the courts and that the Michigan judiciary hence plays an integral role in reviewing the legality of agency actions. The ruling places a direct check on the power of state agencies to interpret and to act upon laws passed by the Michigan Legislature.
The decision is a landmark in Michigan jurisprudence, particularly since it diverges from federal jurisprudence, which grants almost unlimited power to federal agencies in implementing laws passed by Congress. The court's ruling was substantially in agreement with the arguments presented in this brief.