Oral arguments have concluded in a case that could see the US Supreme Court strike down the insurance requirement that underpins President Barack Obama's healthcare overhaul.
At the end of six hours of oral arguments on Wednesday, no clear consensus emerged for the fate of the wide-ranging law should the court's nine justices invalidate its key provision: the mandate that most US citizens obtain medical insurance by 2014 or face a penalty.
The court is expected to rule by late June on the fate of the law, considered Obama's signature domestic policy achievement.
On Wednesday, the last of three days of historic arguments, the court appeared split, with Republican-appointed conservatives doubting the law would survive and the Democratic-appointed progressives offering a strong defense for the
If even one of the five conservative Republican appointees joins the four progressive Democratic appointees on the court, the law would be upheld. If the five conservatives stay united, the law would fall.
The law, which constitutes the US healthcare system's biggest overhaul in nearly 50 years, seeks to provide health insurance to more than 30 million previously uninsured Americans and to control soaring medical costs.
As with Tuesday's arguments about the mandate to buy insurance, the fate of the remainder of the law appeared to rest with potential swing voters conservative Justice Anthony Kennedy and conservative Chief Justice John Roberts.
Some 26 US states are challenging the law, arguing that the rest of Obama's healthcare overhaul must go if the court strikes the insurance requirement.
Paul Clement, their advocate before the Supreme Court, told the justices that the so-called individual mandate to obtain insurance or face a penalty was "essential to the entire scheme".
Discerning legislative intent
That sentiment was shared by conservative Justice Antonin Scalia, who made clear that he believed if the individual mandate was struck down, the entire law must go.
"My approach would be if you take the heart out of the statute, the statute is gone," he said.
However, the four progressive justices were sceptical about tossing out the sweeping law that has hundreds of other provisions aimed at stemming soaring healthcare costs and expanding coverage, some of them already in effect.
Justice Sonia Sotomayor, one of the four and an Obama appointee to the court, asked whether the court should allow Congress to decide what to do next. "What's wrong with leaving it in the hands of people who should be fixing this, not us?"
Progressive Justice Ruth Bader Ginsburg went further. She said many parts of the law had not been challenged in court. "Why make Congress redo those?"
The law was passed when Obama's fellow Democrats controlled both houses of Congress after a contentious fight with Republicans dead set against it.
The Obama administration's lawyer, Edwin Kneedler, told the court that if the mandate was struck down, only two key provisions would also have to fall, those related to coverage for people's pre-existing conditions and limiting costs for those patients with a past medical history.
The justices are expected to meet in private on Friday to discuss the issues heard during the arguments this week and take a preliminary secret vote on how they plan to rule. The justices will then begin drafting their written opinions in the private confines of their chambers.
As the court began its last day hearing arguments on the law - six hours spread over three days making it the longest on a single issue in more than 44 years - the crowd of supporters and protesters outside the high court was smaller and more subdued.
The Supreme Court's decision could have huge ramifications for the November 6 presidential and congressional elections as Obama seeks a second four-year term. If the law is upheld, it would be a major vindication for him but if it fails, it would likely be seen as a major setback.
The Republican candidates vying for their party's nomination to face Obama in November all oppose the law and could fight even harder to repeal it if the court leaves in place the entire statute.