Supreme Court justices battled Wednesday over the fate of US President Barack Obama's health care reforms, with liberals fighting to salvage the rest of the law if a key provision is declared unconstitutional.
Justice Anthony Kennedy, who often wields the tie-breaking vote, joined the court's conservative wing in questioning whether the law could survive if it is stripped of its key plank -- that all Americans must buy insurance.
But the top court's liberal judges argued that that was a matter for the Congress rather than the court to decide.
"Why should we involve the court in making a legislative judgment," Justice Sonia Sotomayor asked Paul Clement, the lawyer representing 26 states who said the law should be struck down in its entirety.
Sotomayor argued it might be better to let Congress fix the law.
"If we strike down one provision, we're not taking that power away from Congress. Congress could look at it without the mandatory coverage provision and say this model doesn't work, let's start from the beginning," she said.
The 90-minute session came on the third and final day of blockbuster hearings into the reforms, which have huge implications for the nation and the 2012 presidential elections.
The justices held a separate hour-long hearing later Wednesday on the reform's expansion of Medicaid, the public insurance program for the poor, which states oppose as coercive because they stand to lose all federal Medicaid funding if they refuse to go along with it.
Solicitor General Donald Verrilli closed the government's case with a final plea: "I ask that the ACA be upheld."
Clement pointed to the law's most controversial provision, a requirement that all Americans buy health insurance, in his rebuttal.
"It's a very funny conception of liberty to force somebody to purchase insurance," he said.
The issue of "severability" -- whether the whole law collapses if one provision is deemed unconstitutional -- took on added impetus amid doubts raised about the so-called "individual mandate."
The states challenging the health care law argue that the individual mandate is "the very heart of the act itself," creating a mammoth subsidy to insurance companies that make possible other requirements of the law.
Those include requirements that companies sell insurance to anyone who applies and forbids them denying coverage to people with pre-existing conditions or raising their rates without limit.
Antonin Scalia, one of the most conservative justices, asked: "Can you see a prior case when we are asked to strike down the heart of the case and leave the rest in effect?"
Kennedy suggested that to leave the law in place without the individual mandate would be an undue exercise in judicial power.
"To impose a risk on insurance companies, that seems to me to be more extreme than striking the whole," he said.
The odds that the court would strike down the mandate appeared higher on Tuesday after Kennedy seemed openly skeptical about its constitutionality. But some analysts said the outcome was less clear after Wednesday's session on "severability."
The health care law -- Obama's signature domestic achievement -- encompasses the most ambitious reform of the troubled US health care system in decades, seeking to extend health insurance to 32 million Americans who now lack it.
But since it was signed into law in 2010, the reform has divided public opinion and emerged as a major issue in the presidential campaign, attacked by Republicans as an assault on individual liberties.
Protesters on both sides of the issue have gathered each day outside the Supreme Court as political luminaries, lawyers and a small sampling of the public have packed the marble columned court room where the black-robed justices preside.
Polls show weak public support for the law, with one tracking poll showing that only one in three Americans currently support the individual mandate.
The justices are not expected to rule on the law before June, meaning that the potentially explosive decision is likely to land right in the thick of the heated presidential campaign.
Source: AFP Global Edition