Washington (CNN) After a long-awaited ruling from a US appeals court on the fate of the Affordable Care Act, this much is clear: the wait will only be longer, and uncertainty over the future of the law that provided new coverage for millions of Americans will only linger.

The New Orleans-based court ruled unconstitutional the individual insurance mandate -- which the federal government was no longer enforcing -- yet refused to resolve the most pressing issue: does that mean the rest of the law is also unconstitutional?

By a 2-1 vote, the appeals panel returned the case to a US district court judge for the start of another round of rulings.

It will now likely be months, perhaps even years, before the US Supreme Court could ultimately resolve the merits of a challenge to the sweeping law known as Obamacare, which guaranteed coverage for people with pre-existing conditions, such as diabetes and cancer, expanded Medicaid, and allowed children to stay on their parents' health insurance plans until they turn 26.

For Chief Justice John Roberts and his eight colleagues, Wednesday's decision all but guarantees they will not face yet another contentious dilemma in the upcoming election year. The Supreme Court already has on its calendar disputes over abortion, immigration, gun control and LGBTQ rights. Last week, they added three cases involving President Donald Trump's effort to block investigators' subpoenas issued to his longstanding accountants and banks.

And Roberts will also be spending part of January at the US Capitol, overseeing the Senate's impeachment trial of Trump

It was during an election year, 2012, that the Supreme Court first took up the constitutionality of the law President Barack Obama signed in 2010. That decision saving Obamacare came on a 5-4 vote but only after Roberts switched his vote in dramatic negotiations with the court's liberals behind the scenes and upheld the law as a tax.

He joined the four liberal justices, over protests of his conservative brethren, to uphold the individual insurance mandate. The scars of that internal fight, and some public criticism from conservatives, have not fully healed.

But now, new pressure on the Supreme Court to resolve the new controversy may extend beyond the 2020 presidential election. That would likely be a relief to a chief justice who has tried to shield the court from the polarization of today's Washington. In public appearances, he has increasingly declared that the justices do not engage in politics and should be regarded as neutral decision-makers, unbound from the presidents who appointed them.

In Wednesday's ruling, the two judges in the majority affirmed US District Court Judge Reed O'Connor's 2018 decision against the individual insurance mandate but shunned his decision invalidating the whole law. They said O'Connor failed to sufficiently weigh which provisions Congress intended to tie to the individual mandate.

Judges Jennifer Walker Elrod and Kurt Engelhardt, both Republican appointees, said O'Connor did not do "the necessary legwork of parsing through the over 900 pages of the post-2017 ACA, explaining how particular segments are inextricably linked to the individual mandate." They said he must "employ a finer-toothed comb" for "a more searching inquiry into which provisions of the ACA Congress intended to be inseverable from the individual mandate."

Those judges also criticized the Trump administration, which has been trying to kill Obamacare, for shifting positions throughout the litigation. At the same time, their decision spares the administration from an escalating legal battle in the upcoming election year.

Where the case is headed

Roberts' original ruling in 2012 is one factor that generated the current lawsuit.

Texas and other Republican-led states had sued to eliminate Obamacare after the Republican-led Congress in 2017 cut to zero the tax penalty for people who did not abide by the mandate to buy insurance. When the Roberts majority upheld the individual insurance requirement, it based on Congress' taxing power.

Now, because the individual mandate is no longer tied to a tax penalty, the states and the Trump administration argued, the mandate and the whole law should be struck down.

Judge Carolyn Dineen King, a Democratic appointee, dissented from the appeals court majority's voiding of the insurance requirement and said her colleagues on the panel should have left it at that. She insisted Congress would not have wanted the entire law to fall because of the tax change. Returning the case to a lower court for a "do-over," King said, "will unnecessarily prolong this litigation and the concomitant uncertainty over the future of the healthcare sector."

"It is unlikely that Congress would want a statute on which millions of people rely for their health care and livelihood to disappear overnight with the wave of a judicial wand," King wrote.

Still, Wednesday's decision does ensure that the law that Trump has railed against survives for the near future. If the appeals court panel had affirmed O'Connor's ruling, it would have gutted Obamacare and produced another immediate showdown at the Supreme Court.

Such a ruling also could have incited new criticism against the Trump administration. Many provisions of Obamacare, including those that protect people with preexisting conditions or allow young adults to stay on their parents' policies, remain popular.

Some high court legal action may yet be possible, however.

California Attorney General Xavier Becerra, leading the group of states defending the law, suggested he would petition the Supreme Court to take up the case even before the lower court judges had addressed which parts of the law should be invalidated. It is exceedingly rare for the high court to accept a case that had not yet been aired and resolved by lower court judges.

Judges on the 5th US Circuit Court of Appeals observed that the Trump administration had argued this year that the entirety of the ACA should fall with the individual mandate, a position that marked "a significant change." When the case was argued before O'Connor, the administration said that only the guaranteed-issue and community-rating provisions were inseverable and therefore doomed.

After the ruling, Trump declared on Twitter that his administration "continues to work to provide access to high-quality healthcare at a price you can afford, while strongly protecting those with pre-existing conditions."

But as the appeals court noted when it referred to the administration's shifts throughout the litigation, the Trump administration's legal position, in fact, would not have protected people with pre-existing conditions.