A group of small business owners who challenged the legality of the Affordable Care Act over a tax-credit provision has seen its lawsuit rejected by  Judge Paul Friedman of the U.S. District Court for the District of Columbia.

Their lawsuit contended that language in the ACA precluded the federally run exchange HealthCare.gov from awarding tax credits for lower-income Americans, pointing to a sentence that says such credits are available to those who buy insurance "through an exchange established by the state."

"The plain text of the statute, the statutory structure, and the statutory purpose make clear that Congress intended to make premium tax credits available on both state-run and federally facilitated exchanges," Friedman wrote in a ruling issued Wednesday.

The lawsuit filers were scattered among six states that don't operate health care exchanges (marketplaces). Their attorney, Sam Kazman of the Competitive Enterprise Institute, said they will appeal the decision.