AP

WASHINGTON SUPREME Court justices on Monday began hearing arguments on President Barack Obama’s health care overhaul, a law that touches core political divisions in the United States and will have a major impact on the life of virtually every American.

Since Obama signed the hugely controversial legislation into law two years ago, 26 states have challenged the constitutionality of the overhaul, the largest expansion in the nation’s social safety net in more than four decades.

Republicans have made repealing the law central to their bid to deny the president a second term in the November election.

All four Republicans battling for the nomination to challenge Obama have promised to undo the health care overhaul, provided the conservative- dominated Supreme Court doesn’t strike it down in a decision that is expected in June.

The fight against the law, aimed at extending health insurance to more than 30 million Americans, has further inflamed deep divisions in a country knocked off kilter by the Great Recession and embroiled in a political battle about the role of government.

Demonstrators chanted outside the court on Monday.

“Care for you, care for me, care for every family,” supporters shouted. A half-dozen opponents yelled, “We love the Constitution!” Until the health care law, the United States was the only major developed country without a national health care system.

Republicans are leading the fight to kill the law either via the court or through congressional repeal. They say the worst fears about what they derisively call “Obamacare” already have come to pass in the form of higher costs and regulations, claims that the law’s supporters dispute.

Polls have consistently shown the public is at best ambivalent about the benefits of the health care law and that a majority of Americans believe the insurance requirement is unconstitutional.

The hearings this week will be closely followed for clues about what the nine Supreme Court justices are thinking.

The court has four liberalleaning justices appointed by Democratic presidents‚ two by Obama‚ and five conservatives appointed by Republican presidents. In order for the law to stand as written, at least one of the conservative justices will have to join the liberals in ruling to uphold the law.

People hoping for a glimpse of the action waited in line all weekend for the relatively few seats open to the public. The justices allotted the case six hours of argument time, the most since the mid-1960s.

The usual time is an hour, with 30 minutes for each side.

The court, which has steadfastly denied access to television cameras, will release audio recordings of the arguments on the same day they take place.

The first time that happened was when the court heard arguments over ballots in Florida in a case that decided the 2000 presidential election in favour of George W Bush. The last occasion was the Citizens United case that freed businesses and labour unions to spend unlimited money in the current presidential contest.

The first arguments on Monday concern whether the justices may rule at all. A judicial ruling from 1867 could give the court reason to delay a ruling.