U.S. District Judge Reed O'Connor declared that Congress made the law unconstitutional in 2017 by zeroing out the tax levied on people who don't have insurance.
Attorneys for states hoping to save President Barack Obama's health care law have been hit with some intense and occasionally skeptical questioning from appellate judges in a New Orleans federal court.
The hearing at the USA 5th Circuit Court of Appeals - which pits blue states defending the law against red states and the Trump administration seeking its repeal - has also raised the possibility that the healthcare law, often called Obamacare, might survive in only parts of the country.
The judges hearing the arguments were 5th Circuit Judges Carolyn Dineen King, Jennifer Walker Elrod and Kurt Engelhardt.
Douglas Letter, arguing for the now-Democratic-controlled House of Representatives, said Texas and the other Republican-led states are exaggerating the effectof the tax law.
"The greater lesson is that the judges today seem very focused on staying consistent with the law and faithful to their job to uphold the Constitution, but not to come in as a super legislative body to just rewrite the Affordable Care Act", Henneke said.
When the administration first weighed in on the case, in June 2018, it said it believed that without the tax penalty only the ACA provisions most closely connected to that penalty - including requiring insurers to sell policies to people with preexisting conditions - should be struck down.
Republicans in Congress subsequently failed to overturn Obamacare, but in December 2017, Trump signed into law a tax bill passed by a Republican-led Congress that reduced the tax penalty to zero dollars.
Working to save the law are 20 states, led mostly by Democrats, including California, which has used the law to engineer a dramatic expansion of insurance coverage.
Make no mistake, we argued against congressional action to zero out the individual mandate two years ago because it has been a helpful part of the ACA, spurring young, health people to buy health insurance, which not only protects them from medical and financial disaster but makes premiums more affordable for everyone by balancing out the risk pool.
Chief Justice John Roberts in 2012 famously upheld Obamacare by declaring it legal as a tax. Justice Department officials argued at the time thatthe law's insurance requirement and consumer protections were no longer valid without any penalty but that other parts of the law should stand.
The fate of the Affordable Care Act is in the spotlight once again as a federal appellate court hears oral arguments in a lawsuit backed by President Donald Trump's administration that seeks to overturn the 9-year health care law.
Flentje said the administration is "appreciative" that the district judge put his ruling on hold, stressing that if the Affordable Care Act falls, a lot must be sorted out.
Court decision could affect health care coverage for millions of Americans; Casey Stegall reports. King was nominated to the appeals court by President Jimmy Carter in 1979. The law now protects those individuals from denial of coverage or steeper prices because they have chronic illnesses.
The Democratic-led House of Representatives has also been granted intervenor status in the case. For example, the law established a new federal office to support experiments by physicians and hospitals to improve quality and lower healthcare costs.
Obamacare, formally called the Affordable Care Act, was one of the most consequential healthcare measures in United States history.