Lawyers for the elderly and disabled are headed back to Arizona, where they hope a federal judge doesn’t change his mind in a case that affects millions of Medicare beneficiaries.

Two years ago, U.S. District Judge Alfredo Marquez held that Medicare patients have a constitutional right to go to court if HMOs deny treatment or other services. Specifically, he said such denials constitute a “state action” — invoking constitutional protections — because HMOs are acting as agents of the government when they contract to provide Medicare benefits.