The Affordable Care Act - also known as Obamacare - is back before a federal court Tuesday, facing the biggest legal challenge to the the health care overhaul since a Supreme Court decision in 2012.
The ACA, which expanded health care coverage to millions of Americans, included a controversial - and some say essential - element called the individual mandate, which required individuals purchase health insurance.
But then in 2017, this happened: (SOUNDBITE) (English) U.S. PRESIDENT DONALD TRUMP, SAYING (DECEMBER 21, 2017): "We essentially repealed Obamacare, because we got rid of the individual mandate, which was terrible.
And that was a primary source of funding of Obamacare." As part of a massive tax overhaul, Republicans in Congress eliminated the penalties created under Obamacare for those who did not buy health insurance.
Republican state attorney's general filed a new lawsuit saying that without the penalties, there was no more individual mandate.
And without that mandate, Obamacare had to go.
Reuters correspondent Nate Raymond.
(SOUNDBITE) (English) REUTERS CORRESPONDENT NATE RAYMOND, SAYING: "A federal judge then in December of 2018, Judge Reed O'Conner of Fort Worth, he agreed.
He agreed not only that the individual mandate was unconstitutional, but he said that it was an essential part of Obamacare and it couldn't be severed from the law.
And so the entire law had to be struck down." That decision was appealed by Democratic lawmakers It's now before the 5th Circuit Court of Appeals in New Orleans.
Ahead of the arguments over Obamacare Tuesday, the Trump Administration took a hard line, putting out a legal brief agreeing with the Texas judge that the whole law should be invalidated.
But they might be careful what they wish for.
(SOUNDBITE) (English) REUTERS CORRESPONDENT NATE RAYMOND, SAYING: "I think there are some signs that the Trump administration is aware that if they actually got what they're truly advocating for in this brief there would be some pretty wild repercussions throughout the healthcare system." Republicans have repeatedly failed to muster enough of their party to kill the law in Congress, or agree on a replacement.
Meanwhile, aspects of Obamacare - such as protections for pre-existing conditions and an expansion of the Medicaid program - have proved increasingly popular.
(SOUNDBITE) (English) U.S. PRESIDENT DONALD TRUMP, SAYING (MARCH 29):"We're gonna always take care of pre-existing conditions.
Just remember that." A fifth-circuit decision might come in the fall.
Any way the court rules will likely go before the Supreme Court.
If the nine justices are again asked to weigh maintaining Obamacare, they could deliver their decision in the summer of 2020, in the heat of the presidential race.