A US court has dealt a new blow to the health care reform law seen as President Barack Obama's proudest domestic achievement, declaring its centerpiece provision unconstitutional.
The Eleventh Circuit appeals court, based in Atlanta, ruled Friday that the law's individual mandate, which requires everyone to own health insurance in America's mostly private system or pay a penalty, exceeded Congress's powers.
But the court ruled that the remainder of the health care law, which extended coverage to an extra 32 million people and was a long-held dream of Democrats, was within the bounds of the Constitution.
About 50 million Americans lack basic health insurance. As a result, hospitals and taxpayers are forced to pay about $43 billion a year to cover the costs of those who are treated but cannot pay.
The ruling increased the likelihood that the US Supreme Court will be called upon to rule on the health care law's constitutionality, possibly as soon as next year, in the heat of a presidential election campaign.
Republicans strongly oppose the law, which they have dubbed "Obamacare," as an infringement on individual liberty, and have sworn to repeal it.
By a 2-1 margin, the Eleventh Circuit affirmed a ruling by a lower Florida court that the individual mandate was unconstitutional, in a case brought by 26 state governors and attorneys general, most of them Republican.
But the judges overturned another part of the Florida court's ruling that the entire health care law, passed in 2010, was unconstitutional.
"The individual mandate exceeds Congress's enumerated commerce power and is unconstitutional," wrote Chief Judge Joel Dubina.
"This economic mandate represents a wholly novel and potentially unbounded assertion of congressional authority: the ability to compel Americans to purchase an expensive health insurance product they have elected not to buy, and to make them re-purchase that insurance product every month for their entire lives."
The White House said it strongly disagreed with the decision and was confident that the law would ultimately be upheld as constitutional.
It also pointed out that four courts, including the Sixth Court of Appeals, had endorsed the law.
"Those who claim this provision exceeds Congress's power to regulate interstate commerce are incorrect," said Stephanie Cutter, a special assistant to Obama.
She argued that those who chose not to buy insurance in the US private medical system hurt everyone else, because taxpayers end up subsidizing their care when they are taken to emergency rooms.
The White House also justifies the individual mandate by saying that without it, people would wait until they get sick to apply for coverage, which would cause insurance premiums for everyone to rise.
But the ruling cheered Republicans who see the health care law as an unacceptable intrusion by government into individual freedoms.
"Forcing Americans to buy health insurance approved by the government was an unprecedented, unwelcome, and unconstitutional expansion of federal power," said Mitch McConnell, the top Republican in the Senate.
Rick Perry, the conservative Texas governor who is launching a presidential campaign this weekend, described the law as an "egregious violation of our constitutional rights."
Republican House of Representatives Speaker John Boehner vowed to repeal "the entire abomination."
Though the health care law is one of Obama's most significant achievements, its controversial nature means he has reaped little gain from a victory that required a huge investment of political capital.
A CBS News poll taken in June found that 37 percent of those asked approved of the health care law, while 48 percent opposed it.