File photo: US President Barack Obama. (Agence France-Presse)
A sharply divided US Supreme Court weighed the future of "Obamacare" for a second time in three years Wednesday after a new challenge to the contentious healthcare reform.
The law, President Barack Obama's crowning domestic achievement, seeks to make health insurance available to a broad cross-section of Americans, for whom health care is often too expensive or otherwise inaccessible.
In June 2012, the first time the Supreme Court considered a challenge to Obamacare, its conservative Chief Justice John Roberts helped save the measure by voting alongside the four more progressive justices.
The president's Republican foes have tried various tactics to repeal the law, but their latest challenge in the US high court focuses on the wording of a statute of the law that governs federal tax subsidies for people who sign up for Obamacare coverage.
The narrow question before the court is whether some seven million people who signed up for Obamacare via the government's website are actually entitled to tax subsidies that make the coverage affordable.
Legal scholars say that a ruling against the tax credits provision would eviscerate the law so thoroughly that it would be tantamount to striking down the measure altogether.
Predictably, the nine justices seemed to divide again roughly along partisan lines, although Roberts, who asked hard-hitting questions of both sides during the case three years ago, sat sphinx-like throughout Wednesday's arguments, saying almost nothing.
Judge Sonia Sotomayor, one of the more left-leaning members of the high court, warned that striking down the provision could lead to a "death spiral that this statute wanted to avoid."
Another justice, Anthony Kennedy, often the fulcrum of the court who sometimes sides with liberals and sometimes with conservatives, posited that invalidating the statute would raise "a serious constitutional problem" if citizens suddenly found themselves without subsidized insurance.
In later remarks however, Kennedy seemed troubled by the "ambiguity" in the wording of the Obamacare measure, suggesting perhaps that he might after all be open to striking it down.
A vote to do so would find him in the company of the court's bloc of three most conservative members who are certain to go against the Obamacare again this time -- Justices Antonin Scalia, Clarence Thomas and Samuel Alito.
The Affordable Care Act, passed in 2010, came into force in January 2014.
Since then, Americans without health insurance have been able to obtain insurance through their home state or the federal Department of Health and Human Services, which set up the healthcare.gov website.
But out of the 50 US states, 34 -- most of which are Republican governed -- have refused to create state health insurance "exchanges" or online marketplaces, requiring their residents to sign up for Obamacare on the federal government's website.