If the Supreme Court breaks down along its usual ideological lines on the vote on the health care law, Justice Anthony Kennedy -- known as the swing vote on the court -- could be the one to decide whether the government can require almost every American to buy health insurance or pay a fine.
When the court hears the case on the Affordable Care Act in March, advocates, experts and the media will parse every question from Kennedy, hoping for a hint of his views on the merits of the case.
The central focus will be on the individual mandate, the key provision that requires individuals to buy health insurance by 2014 or pay a tax penalty.
As its principal argument that Congress has the authority to enact the mandate, the administration relies on the Commerce Clause of the Constitution that says in part: "The Congress shall have power ... to regulate commerce with foreign nations, and among the several states and with the Indian tribes."
Critics of the health care law argue that while Congress has substantial power to regulate interstate commerce, it may not compel people into the marketplace and force them to buy a product.
Paul D. Clement, a lawyer from Bancroft PLLC, who is representing the 26 states challenging the law, writes in court briefs, "In the over 200 years that Congress has sat, it has never before attempted to exercise its Commerce Clause power in this manner."
Kennedy, 75, who was appointed to the court in 1988 by Ronald Reagan, has often been the deciding vote in big cases. But the Supreme Court has never heard a case quite like the challenge to the Affordable Care Act, and predictions regarding the final vote count have varied significantly.
Many were surprised when two appellate court judges, with sterling reputations in conservative circles, voted to uphold the constitutionality of the mandate when a similar challenge came before their courts.
The case -- with an unprecedented 5½ hours of argument allotted to it -- could defy expectations.
Justice Kennedy the Swing Vote
Scholars have scoured Kennedy's previous cases for hints on how he might rule. They point out that it's not always easy to forecast Kennedy's vote on particular cases and that the term "swing vote" can be misinterpreted.
"I would reject equating swing vote with lack of clarity," says Michael C. Dorf, a professor at Cornell University Law School and a former Kennedy law clerk. "Being the swing vote is simply an artifact of who the other eight justices are. On some issues, free speech for example, he's very liberal. On gay rights, he's been very liberal, out ahead of the court. On other issues, he's been conservative -- the Establishment Clause, for example," which prohibits a national religion for the United States.
Neil S. Siegel, a professor at Duke Law, says Kennedy "cares about a number of different things and oftentimes they are conflicting. He cares about robust federal power to regulate markets, he cares about robust federal power to create and maintain an integrated national economy. But at the same time that he cares about federalism, he cares about states' power. He cares about individual liberty, and the role that federalism plays in preserving it."
"I think it's fair to say he resists absolutes in most areas of the law. That makes him a little less easy to pigeonhole," Dorf says.
Although previous Supreme Court cases regarding guns in schools, violence against women and medical marijuana may seem far afield of the health care debate, they offer insight into Kennedy's views on the scope of congressional power.
Lopez and Morrison
From 1937 until 1994, the court upheld Congress' broad power to legislate pursuant to the Commerce Clause.
But then came United States v. Lopez and United States v. Morrison, two cases in which the court ruled that Congress had exceeded its authority under the Commerce Clause.
In both cases, Kennedy voted with the majority.
Lopez, decided in 1995, involved a law that made it a federal offense to possess a fire arm within 1,000 feet of a school zone.
The government argued that the possession of a firearm in a school zone could result in violent crime and that violent crime could be expected to affect the national economy. The court rejected the argument, ruling "The possession of a gun in a local school zone is in no sense an economic activity that might, through repetition elsewhere, substantially affect any sort of interstate commerce."
Kennedy voted with the majority but also issued a concurring opinion: "The statute makes the simple possession of a gun within 1,000 feet of the school a criminal offense. In a sense any conduct in this interdependent world of ours has an ultimate commercial origin or consequence, but we have not yet said the commerce power may reach so far," Kennedy wrote.
Siegel says Kennedy's concurrence reflects "that there are limits on the scope of Congress' commerce power, but they are modest limits. Congress complies with those limits as long as it is regulating the market."
The Morrison case involved a provision of the Violence Against Women Act that allowed victims of gender-motivated violence to sue in federal court. The court relied on much the same reasoning as in Lopez, and struck down the provision.
Randy Barnett, a professor at Georgetown University Law Center who is also representing a small-business group that is opposed to the health care law, says, "Justice Kennedy joined Chief Justice Rehnquist's 1995 opinion in Lopez -- a five-four decision -- holding that there were judicially enforceable limits on the power of Congress -- a proposition that had been in doubt for 60 years but which was reaffirmed in the 2000 case of Morrison."
In Lopez and Morrison, the court ruled that Congress had exceeded its authority. But supporters of the health care law point to another recent case in which the court upheld a law based on Congress' power under the Commerce Clause.
In Gonzales v. Raich, the court ruled that federal anti-drug laws could be applied to prohibit the local cultivation of marijuana for medical purposes, which had been authorized under state law.
The court held that even the homegrown cultivation and possession of the drug used solely to alleviate the chronic pain of people like Angel Raich would undercut Congress' regulation of interstate economic activity.
"Our case law firmly establishes Congress' power to regulate purely local activities that are part of an economic class of activities that have a substantial effect on interstate commerce." Justice John Paul Stevens wrote. Kennedy joined the opinion.
Dorf differentiates Kennedy's votes in Lopez and Raich, saying that Kennedy understood in Raich that marijuana was part of a national market.
"There actually is an argument for a national response to a national and international drug market, in a way that's different from guns near schools. Kennedy was persuaded by the government's argument that it's not purely intrastate" said Dorf.
"I think Raich is important," says Siegel, "because it illustrates Justice Kennedy's principal concerns when it comes to the commerce power. He's prepared to give Congress wide latitude when Congress is regulating markets."
Federal Judge Jeffrey Sutton, a George W. Bush appointee and former clerk to Justice Antonin Scalia, sits on the U.S. Court of Appeals for the Sixth Circuit. Sutton was the first judge nominated by a Republican president to vote in favor of the mandate when a similar case came before him. He relied in part upon the Raich case.
Sutton wrote, "And if Congress could regulate Angel Raich when she grew marijuana ... for self-consumption, indeed for self-medication, and if it could do so even when California law prohibited that marijuana from entering any state or national markets, it is difficult to see why Congress may not regulate the 50 million Americans who self-finance their medical care."
But Barnett, who also represented Angel Raich, says that the Raich decision was not the final word from Kennedy on the scope of Congress' power.
The Mentally Ill and the Necessary and Proper Clause
"Some people might have been tempted to say that after Kennedy joined Stevens in the Raich case, without any separate opinion, that he may have given up on policing the limits on Congress' power," says Barnett.
Barnett points to another case dealing with the Necessary and Proper Clause of the Constitution. The provision grants Congress the authority "to make all laws which shall be necessary and proper for carrying into execution "the powers of Congress outlined in the Constitution."
In United States v. Comstock, the court upheld a federal civil-commitment statute authorizing the Department of Justice to detain a mentally ill, sexually dangerous federal prisoner beyond the date the prisoner would otherwise be released. The respondents in the case had argued that Congress had exceeded its authority.
"The court is correct" Kennedy wrote in agreement to hold that the challenged portions of the statute "are necessary and proper exercises of congressional authority."
But he also wrote to express caution "that the Constitution does require the invalidation of congressional attempts to extend federal powers in some instances."
"He's reaffirming his approach in Lopez that the powers of Congress are limited and courts have a role in policing those limits," says Barnett.
Arguments in the Affordable Care Act will be held over two days in March. That the court ordered 5½ hours of argument reflects the complexities of the challenge to the health care law. The justices will consider the mandate as well as several other issues pertaining to the signature legislative achievement of the Obama administration.
The only other recent case to gain such attention from the public was the closely divided case of Bush v. Gore, which pertained to recounting the Florida votes in the 2000 election.
The decision in the heal care law is expected to come down at the beginning of summer, smack in the heart of the 2012 presidential campaign.