U.S. District Judge Reed O’Connor didn't issue an immediate ruling Wednesday after listening to arguments for nearly four hours about whether to find the Affordable Care Act unconstitutional.

U.S. District Judge Reed O’Connor did not render a decision Wednesday on a high-profile case that centers on whether the Affordable Care Act is constitutional.

RELATED: All eyes on Texas as oral arguments begin in lawsuit that seeks to invalidate the Affordable Care Act

Ken Paxton, the Texas attorney general who is leading the court challenge on behalf of 20 Republican governors and state attorneys general, argued during the four-hour hearing that the law became unconstitutional when Congress enacted President Donald Trump’s tax overhaul and eliminated the tax penalty as part of the law’s individual mandate that required most Americans to buy health insurance.

He asked O’Connor to issue a preliminary injunction, temporarily ending enforcement of the law, until the case is decided. However, Justice Department Attorney Brett Shumate opposed the preliminary injunction, telling O’Connor that it “could throw the health care markets into chaos," according to The Dallas Morning News.

Although the United States is the defendant, the Justice Department has said it will no longer defend the individual mandate or other provisions, such as coverage of pre-existing conditions. Therefore, it was up to Xavier Becerra, California’s attorney general, who argued on behalf of a coalition of 17 other attorneys general that the mandate remains constitutional.

During yesterday’s hearing, O’Connor focused on the question of legislative intent. He indicated he would render a decision “as soon as I can,” The New York Times reported. But The Texas Tribune noted that in the past O’Connor has ruled against the Affordable Care Act on narrower grounds. If he sides with the plaintiffs, the case may make its way to the Supreme Court.

Editor’s note: Read more on pre-existing conditions and the future of health care reform here. To learn how other plans are adapting to marketplace changes, check out our upcoming live events: RISE West, for strategies and solutions for risk adjustment, quality performance improvement and compliance; and The 12th Risk Adjustment Forum, for innovative strategies to improve risk adjustment programs for Medicare Advantage, Medicaid, and Commercial Plans.