President Obama has won a major victory in the battle to preserve his landmark political achievement: Obamacare.
The Supreme Court decided, by six votes to three to uphold tax subsidies which are crucial to his signature healthcare law.
The challenge to the law was considered by many to be a technicality brought against it by Mr Obama's many political enemies.
However, the court ruled that the 2010 Affordable Care Act did not restrict the subsidies to states that establish their own online healthcare exchanges.
This is the the second time in three years that the America's highest court has ruled against a major challenge to the law brought by conservatives seeking to defeat it through the judicial system.
The case centered on the tax subsidies offered under the law, passed by Mr 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.
President Obama has now urged Republicans to accept ObamaCare as law and to move on, with limited success.
John Boehner, a leading Republican, claimed that the law was "fundamentally broken".
He said: "We will continue our efforts to repeal the law and replace it with patient-centered solutions that meet the needs of seniors, small business owners, and middle-class families."