The U.S. Supreme Court on Thursday, June 25, upheld the nationwide availability of tax subsidies that are crucial to the implementation of President Barack Obama’s signature healthcare law, handing a major victory to the president.

The court ruled on a 6-3 vote that the 2010 Affordable Care Act, widely known as Obamacare, did not restrict the subsidies to states that establish their own online health care exchanges. It marked the second time in three years that the high court ruled against a major challenge to the law brought by conservatives seeking to gut it. Chief Justice John Roberts was joined by fellow conservative Justice Anthony Kennedy and the court’s liberal members in the majority.

The decision means the subsidies will remain not just in the 13 states that have set up their own exchanges and the three states that have state-federal hybrid exchanges, but also in the 34 states that use the exchange run by the federal government.

The case centered on the tax subsidies offered under the law, passed by Obama’s fellow Democrats in Congress in 2010 over unified Republican opposition, that help low- and moderate-income people buy private health insurance. The exchanges are online marketplaces that allow consumers to shop among competing insurance plans.

The question before the justices was whether a four-word phrase in the expansive law saying subsidies are available to those buying insurance on exchanges “established by the state” has been correctly interpreted by the administration to allow subsidies to be available nationwide.

Roberts wrote that although the conservative challengers’ arguments about the plain meaning of the statute were “strong,” the “context and structure of the act compel us to depart from what would otherwise be the most natural reading of the pertinent statutory phrase.”