The Affordable Care Act is under fire again in federal court

The latest legal threat to the 2010 law, which has been upheld twice by the Supreme Court, arises from a lawsuit lodged in February by the Texas attorney general and 19 of his GOP counterparts.

The long-disputed fate of former President Barack Obama's health care law was playing out anew in a Texas federal courtroom Wednesday as a score of Republican-led states are seeking to persuade a federal judge to halt the sprawling health-care law.

In a hearing expected to last most of the day, plaintiffs are asking the court to grant a preliminary injunction that would suspend the law while the case is fully heard. The procedural step is typically low-wattage, but if the judge granted an injunction, the outcome would have outsized effects on Americans' health coverage.

The latest legal threat to the 2010 law, which has been upheld twice by the Supreme Court, arises from a lawsuit lodged in February by the Texas attorney general and 19 of his GOP counterparts. The case is before U.S. District Judge Reed O'Connor, who was appointed by President George W. Bush and has ruled against narrower aspects of the health-care law in recent years, such as a provision affecting same-sex couples.

The suit alleges that the health-care law is unconstitutional because of a recent change in federal tax law that will soon end a penalty for Americans who violate the law's requirement that most people carry health insurance.

Wednesday's hearing is significant because an injunction would toss large parts of the nation's health-care system into chaos. Depending on how broad it was, it could block the annual fall shopping period for health plans through the law's insurance marketplaces, stop premium subsidies on which millions of consumers rely, or even reverse a variety of Medicare payment changes built into the law.

The other reason the hearing is drawing substantial attention is the highly unusual position that the Trump administration has taken in the case. The federal government is the suit's defendant, and the Justice Department typically defends existing federal laws when they are challenged. In a sharp break from that tradition, the department in June filed court papers and wrote to congressional leaders, saying it would not defend all of the law against this suit.

Instead, 17 Democratic state attorneys general who have won standing in the case are making the main arguments to defend the federal law.

Texas Attorney General Ken Paxton and his allies contend that the health-care law has become unconstitutional because of a massive tax bill, passed by the Republican-led Congress in December, which calls for the law's penalty for flouting the law's individual insurance mandate to end in January.

They argue that, when the Supreme Court upheld almost all of the health-care law in an important 2012 ruling, the majority reasoned that Congress's authority to set taxes made the insurance mandate constitutional. The plaintiffs in the current suit - in an argument that some legal scholars regard as weak - contend that the penalty's end means that the basis for the high court's decision no longer exists and that the whole law is thus invalid.

The Justice Department's position is part of broad efforts by President Donald Trump and his aides to undermine the law that was Obama's main domestic achievement. The president and health officials also have cut spending on efforts to encourage consumers to buy ACA coverage, intended for people who cannot get affordable health benefits through a job. And they are working to make it easier for people to buy inexpensive health plans that skirt benefits and consumer protections required under the law.

But Justice's argument does not go as far as the plaintiffs'. The department's June court filing contended that the law's provision requiring most Americans to carry health insurance soon will no longer be constitutional once the penalty ends and that, as a result, consumer insurance protections under the law will not be valid, either.

The administration's position would end a part of the law that prevents insurers from charging more to people with preexisting medical conditions - or refusing to sell them coverage. Democrats have latched on to strong public support for that protection as an issue in the approaching midterm congressional elections.

But unlike the plaintiffs' argument, the Justice brief said that many other aspects of the law can survive because they can be considered legally distinct from the insurance mandate and consumer protections.

In a conference call for reporters before the hearing, California Attorney General Xavier Becerra and several allies maintained that the health-care law remains constitutional because, by lowering the law's penalty to zero, Congress did not permanently remove the tax. Even if the judge found that the tax no longer existed, they argued, that could be legally separated from the rest of the statute.