The US Supreme Court Tuesday took up the most contentious part of President Barack Obama's landmark health care reform, hearing arguments on whether it is constitutional to require Americans to buy insurance coverage.
The second day of an unprecedented three days of arguments into the Affordable Care Act, derided by opponents as "Obamacare" but hailed by supporters as a major achievement, has focused national attention on what could be a decisive issue in the 2012 presidential elections.
The nine justices opened the two-hour session after the customary call to order -- "Oyez, oyez, oyez" -- to a packed house in the august marble columned court, America's ultimate arbiter on all matters of law.
In what is perhaps the court's biggest case since it had to decide on the Al Gore versus George W. Bush 2000 election, solicitor General Donald Verrilli is presenting the administration's case that the new law does not flout the US Constitution.
He was arguing that the reforms, which expand health care coverage to 32 million Americans who are currently uninsured, fall within Congress's rights to regulate interstate commerce -- in this case health insurance -- and to enforce it with penalties.
Paul Clement, a former solicitor general, is arguing for 26 states who are challenging the law on the grounds that the so-called "individual mandate," requiring the purchase of insurance, is an assault on personal freedoms guaranteed under the constitution.
As the session got underway, protesters for and against the law held demonstrations on the steps of the court, reflecting the intense passions the law has aroused in an election year.
Tuesday's session followed oral arguments Monday in which the justices appeared to satisfy themselves they had jurisdiction to review the law even though it does not enter into full effect until 2014.
On Wednesday, they will take up two other issues separately -- whether the law as a whole can survive if the "individual mandate" is found to be unconstitutional and whether the government can require the states to extend Medicare -- a federal program for low-income Americans -- to a larger pool.
The individual mandate is a linchpin because it requires that all Americans maintain minimum insurance coverage from 2014, or pay a fine.
The administration has argued that attempts by states to reform health care have largely failed without the individual mandate, and to reform the interstate insurance market it must be able to require that almost all individuals obtain coverage.
In response, Clement has argued that upholding the individual mandate, forcing people to buy a product they do not want, would revolutionize the relationship between the government and the individual.
"If this is to remain a system of limited and enumerated federal powers that respects individual liberty, accountability and the residual dignity and sovereignty of the states, the individual mandate cannot stand," he wrote.
The provision has made Obama's greatest legislative achievement the Republicans' biggest target going into the November presidential election.
Supporters hail the law -- the most sweeping reform of the troubled US health care system in decades -- as a major social advance, while opponents view it as an assault on individual liberties, deriding it as "Obamacare."
The area around the court remained a focus for protests on both sides, with several hundred people outside for a second day, some chanting, praying or singing.
Twenty-three-year-old Abby Hoffman of North Carolina said she was there because "health care is a human right."
But on the other side, acknowledged Tea Party loyalist Diana Reimer of Pennsylvania said the government should not be allowed to order people to buy health insurance.
"I was raised to deal with my own problems, solve my own problems, and never did I go to the government to solve my problems," she said.
Explore further: Supreme Court takes up heart of Obama health law