The U.S. Supreme Court on Thursday 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 healthcare 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.