-Individual mandate upheld
-Expansion of Medicaid limited but not struck down
-Five justices voted to uphold the law: John Roberts (chief justice), Ruth Bader Ginsburg, Elena Kagan, Sonia Sotomayor, Stephen Breyer
-Four justices dissented: Antonin Scalia, Anthony Kennedy, Clarence Thomas, Samuel Alito
The court upheld a core requirement known as the "individual mandate" that Americans buy insurance or pay a fine.
Of the nine justices on the bench, Chief Justice John Roberts' vote was decisive in the Supreme Court's 5-4 ruling in favour of the law.
The ruling comes months before the US election, with Republicans vowing to push for a repeal of the bill.
Healthcare is a deeply polarising issue in the US and Republicans strongly opposed Mr Obama's legislation.
The state of Florida, along with 12 other states, filed a legal challenge to the bill minutes after Mr Obama signed The Patient Protection and Affordable Care Act (ACA) into law in March 2010.
They were later joined by 13 more states, the National Federation of Independent Businesses and several individuals.
'Implement and improve'
Speaking afterwards, President Obama called the court's decision a victory for the country, saying people would not need to "hang their fortunes on chance" or fear financial ruin if they became sick.
"The highest court in the land has now spoken. We will continue to implement this law and we'll work together to improve on it where we can," Mr Obama said, speaking at the White House.
"What we won't do - what the country can't afford to do - is re-fight the political battles of two years ago or go back to the way things were. With today's announcement, it's time for us to move forward.
|US President Barrack Obama|
This ruling means President Obama avoids a humiliating shellacking and does not have to make a near impossible decision about how to replace an eviscerated law. He can wipe his brow and breath a huge sigh of relief. But that does not mean it is bad news for Mitt Romney. The only way to get rid of the law is to elect him. He now has a cause that not only fires up his supporters but may also appeal to all important swing voters. It is, as he has said, a choice.
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