The suit also challenges what it says is President Obama’s unlawful giveaway of roughly $175 billion to insurance companies under the law. According to the Congressional Budget Office, the administration will pay that amount to the companies over the next 10 years, though the funds have not been appropriated by Congress. The lawsuit argues that it is an unlawful transfer of funds.

That issue involves subsidies known as cost-sharing reductions, which the federal government pays to insurers on behalf of people whose incomes range from the poverty threshold to two and a half times the poverty threshold ($11,670 to $29,175 a year for an individual).

If the lawsuit is successful, poor people would not lose their health care, because the insurance companies would still be required to provide coverage — but without the help of the government subsidy, the companies might be forced to raise costs elsewhere.

The subsidies reduce the co-payments, deductibles and other out-of-pocket costs that consumers incur when they go to doctors and hospitals.