The U.S. Supreme Court examined Obamacare for the fifth time on Tuesday. This time the case involves a group of insurers who are claiming the government (and thus taxpayers) owe them $12 billion in promised payments for the costs of providing Obamacare.

The Affordable Care Act promised to partially reimburse insurers if they lost money by covering people with preexisting conditions. The law said that the government “shall” make these payments. But in 2015, Congress attached riders to appropriations bills barring the use of the money for the promised payments.

The consequences were profound. By 2017 three-quarters of the original insurance providers were out of business, and several others stopped participating, leaving just six insurance providers and skyrocketing costs.

The insurers went to court, contending the government had cheated them of $12 billion in promised payments. The effort was to compel the Department of Health and Human Services to make the payments. Insurers involved in the case include Moda Health, Blue Cross and Blue Shield of North Carolina, Maine Community Health Options and Land of Lincoln Mutual Health Insurance Company.

Lower courts split on the merits of the legal claims. Oregon-based Moda Health won a $200 million judgment, but the $70 million claim from the now-defunct Land of Lincoln Health was rejected. A divided appellate court last June ruled against the insurers in a combined case, finding that Congress clearly took action to prevent federal payouts to the program.

Earlier this year the U.S. Supreme Court agreed to have the final word on the dispute. Oral argument was heard this week.

Inside the Supreme Court, lawyer Paul Clement, representing the insurers, told the justices that the case involves a “massive government bait-and-switch.”  When the government makes a promise to pay money, he said, it has to “keep its promise.”

Chief Justice John Roberts chimed in: You claim the insurance companies were “basically seduced” into this program, but they have good lawyers. Why didn’t they “insist upon an appropriations provision” in the law before putting themselves “on the hook for $12 billion?”

Clement replied that when the law was written in 2010, anyone who looked at the money-mandating language would have thought that was sufficient. “Now could it have been better … belt and suspenders,” asked Clement. “Sure, but it’s good enough.”

And so went the back and forth arguments. The case is now under submission, and the Supreme Court will decide the case, for or against the insurance companies, shortly.