RICHMOND, Va. - Lawyers for President Barack Obama go to court on Tuesday to try to save the cornerstone of his healthcare overhaul, arguing that the requirement for Americans to buy insurance is constitutional.

A three-judge panel of the US Court of Appeals for the Fourth Circuit will consider whether a lower court was correct in striking down the requirement. But they will not be the final arbiter in a fight that is expected to reach the Supreme Court.

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Legal scholars see the case as pivotal because it is the first to have oral arguments before an appeals courts. That means its ruling could affect other courts and become the first challenge to the law to reach the high court.

The healthcare law, which requires Americans to buy insurance by 2014 or pay a penalty, was a major victory for Obama, one that the Republican party is working to undo in the courts, statehouses and Congress.

Obama's Republican opponents are expected to make the issue a theme during his 2012 re-election bid by arguing it is a costly and unnecessary government expansion. They have already sought to repeal and choke off funds for the law in Congress.

US District Judge Henry Hudson in Virginia last year ruled that Congress exceeded its authority by forcing Americans to buy health insurance, a key piece of the law aimed at keeping premiums low through ensuring everyone buys coverage.

Virginia had passed a law barring the federal government from making its citizens buy health insurance.

The state filed a legal challenge arguing that the federal government cannot penalize citizens for not buying goods or services under the US Constitution's Commerce Clause.

"It will also be important because any future decision from other courts will feel compelled to respond to the Fourth Circuit's reasoning," said Kevin Russell, a former Justice Department appellate lawyer.

"If it is a well-reasoned opinion, it will likely be influential in other courts as well," said Russell, now in private practice. The 4th Circuit is split evenly among judges appointed by Democratic and Republican presidents.

The three-judge panel will not be known until Tuesday morning and the Obama administration's top appellate lawyer, Acting US Solicitor General Neal Katyal, will be arguing on its behalf.

Justices in another US appeals court in Atlanta will likely take note of the arguments when they hear an appeal on June 8 by the Obama administration in a similar lawsuit filed by more than half the US states.

Many Challenges Still Ahead

Republicans in the House of Representatives have tried to repeal Obama's healthcare overhaul, but the president's fellow Democrats control the Senate and have stymied the effort.

So the focus has been turning to the courts, where numerous challenges are pending.

Two federal judges have struck it down, including one who found the entire law unconstitutional in a challenge by 26 states, but several other judges have ruled that it passed muster and upheld it.

In Atlanta, the 11th Circuit Court of Appeals will hear the Obama administration's arguments calling for the reversal of a decision in a multi-state lawsuit that declared the entire healthcare law unconstitutional. The court has yet to decide if a three-judge panel or all judges will hear it.

In the Virginia case, state Attorney General Ken Cuccinelli appealed Hudson's refusal to toss out the entire law, arguing that Congress would not have passed the healthcare reform legislation without the individual mandate and penalty.

While the appeals courts could side with the government argument that those challenging it are being premature because the individual mandate does not take effect until 2014, one legal scholar said they will likely discount that point.

"I think it is a weaker argument for the government, and I think the courts of appeals feel some pressure to sort of move forward on this," said Daniel Ortiz, a law professor at the University of Virginia. "There is some feeling that if you wait until things are really clear, then it would be so disruptive to unwind the thing and change states' expectations."

The three appeals court judges in Virginia will also consider on Tuesday an appeal by Liberty University, founded by conservative evangelical Jerry Falwell, which argued another federal judge in Virginia was wrong to uphold the individual mandate as constitutional under the Commerce Clause.