Jan. 15 (Bloomberg) — People who buy insurance on health exchanges run by the federal government are eligible for tax credits to reduce their premiums, a U.S. judge ruled, dismissing claims that only state-run exchanges can offer the subsidies.

"The plain text of the statute, the statutory structure and the statutory purpose make clear that Congress intended to make premium credits available on both state-run and federally facilitated exchanges," U.S. District Judge Paul Friedman in Washington said in a ruling today dismissing a lawsuit.

The ruling undercuts what one supporter of the Obama health-care law called an "existential" threat to the law. Opponents say it forces consumers and businesses to participate in a program their state governments opted out of.