More than a dozen health insurance companies, some of which have since failed, are suing the federal government for billions of dollars they say they are owed under an Affordable Care Act program designed to incentivize participation in the public exchanges.

In the first of those cases to be decided on the merits, a federal appellate court soon will decide whether the U.S. Health and Human Services Department owes more than $75 million in damages to a failed Chicago-based health insurer, Land of Lincoln Mutual Health Insurance Co.