A US federal appeals court in Ohio upheld the constitutionality of President Barack Obama's controversial health care law Wednesday in the first rejection of several challenges at the appeals court level.
The law, extending coverage to 32 million uninsured Americans, has been bitterly debated and challenged across the United States since Congress passed it last year.
Opponents say a key provision known as the "individual mandate" exceeds Congress's regulatory powers by requiring Americans to either purchase health insurance by 2014 or pay a fine.
But the court disagreed and ruled against a public interest law firm and four Michigan residents who challenged the law.
"We find that the minimum coverage provision is a valid exercise of legislative power by Congress under the Commerce Clause and therefore affirm the decision of the district court," Judge Martin Boyce of the Sixth Circuit wrote in a 64-page opinion.
Legal experts predict that the US Supreme Court will ultimately decide the fate of one of Obama's key domestic achievements.
On April 25, the Supreme Court rejected Virginia's request to immediately rule on whether the law is constitutional.
It marked the second time the nation's highest court denied a request from critics of the law for an expedited review, without the issue being examined thoroughly in appeals courts first.
Two Republican-appointed federal judges -- in Virginia and Florida -- have already declared the law unconstitutional.
But, in another sign of how the rulings have been largely split along party lines, three Democratic appointees have upheld the law -- in Michigan, Virginia and the US capital Washington.
Explore further: Study recommends inmate immunity test