The court ruled the law as whole made subsidies available for people in all 50 states, not just those who bought insurance through a state exchange.
The high court case was the second major challenge to the healthcare law- often known as Obamacare - since its passage.
The decision is major victory for the Obama administration.
"Congress passed the Affordable Care act to improve health insurance markets, not to destroy them," Chief Justice John Roberts wrote in the opinion.
If the law was overturned, 6.4 million Americans would have been at risk of losing aid.
The 2010 law, often known as Obamacare, set up a federally run insurance exchange where Americans who were not covered by employers or other governmental could buy health insurance.
The US Supreme Court is one of the oldest constitutional review courts. Decisions made by the Supreme Court can overturn federal or state laws, if the justices find they are unconstitutional.
That power has led the court to end segregation in schools, legalise interracial marriage, dramatically change how political campaigns are financed and once effectively chose a president.
The court is made up of nine justices nominated by the president and confirmed by the Senate. They have life tenure once confirmed - other countries' high courts have forced retirement ages.
The US high court is now 1/3 female, after adding its first woman justice in 1981. There is also one Hispanic justice and one African-American justice.
source: BBC
Comments