Aetna’s antitrust suit against Blue Shield of Michigan followed DOJ’s investigation into Blue Shield’s use of most-favored nations clauses in insurer-provider contracts, alleging that Blue Shield violated Sherman Act Section 1 and Michigan law by entering into exclusionary contracts with providers that drove up health care costs and inhibited competition. Aetna’s suit began in 2011 and had been set to go to trial on May 26, 2015, but the court dismissed the suit in light of a settlement.