When Katelynn Watkins sued M Class Mining Health Protection Plan for $1 million in unpaid medical bills, the healthcare plan — which construed an illegal act exclusion as barring her claim — insisted that the highly deferential arbitrary-and-capricious standard of review protected its discretionary interpretation of the plan document. But based on close analysis of the Employee Retirement Income Security Act, the 5th District Appellate Court concluded that MC Class Mining LLC, the plan’s administrator and only named …