Protesters rally on March 23, 2016, in support of the Affordable Care Act's contraceptive mandate. (Photo: Diego M. Radzinschi/NLJ)

A decision late Friday declaring the Affordable Care Act unlawful triggered a furious weekend debate about the validity of the ruling and its fate before an appeals court and ultimately before the U.S. Supreme Court.

In the 55-page decision in Texas v. United States, U.S. District Judge Reed O'Connor in Fort Worth, Texas, agreed with 20 states challenging the law that congressional action last year to eliminate the penalty imposed by the individual mandate in the act made it unconstitutional. In the more controversial part of O'Connor's decision, he said that the demise of the mandate rendered the entire law invalid, because it could not be severed from the mandate.

Related: Hospitals, insurers sink as ACA ruling jolts investors

Democratic attorneys general who intervened in the case immediately vowed they would appeal to the U.S. Court of Appeals for the Fifth Circuit, putting the law on the path to review in the next year or so by the U.S. Supreme Court, which upheld the law in 2012. Trump on Monday declared in a tweet: “A confirming Supreme Court Decision will lead to GREAT HealthCare results for Americans!”

O'Connor's ruling arrived at a time when “health insurers have already locked in benefits and prices for 2019 health coverage and are almost done with ordinary applicant enrollment for 2019 coverage,” according to sibling publication BenefitsPRO.

How the Trump Justice Department will handle the case is uncertain; in the Texas case, the U.S. government agreed the mandate was unconstitutional, but disagreed on severability. What follows is a snapshot of what legal scholars and advocates are saying about O'Connor's ruling:

>> Jonathan Adler, professor at Case Western Reserve University School of Law, and Yale Law School professor Abbe Gluck: ”A ruling this consequential had better be based on rock-solid legal argument. Instead, the opinion by Judge Reed O'Connor is an exercise of raw judicial power, unmoored from the relevant doctrines concerning when judges may strike down a whole law because of a single alleged legal infirmity buried within.” [The New York Times]

>> Nicholas Bagley, professor at University of Michigan Law School: ”Nothing changes for the time being. And nothing should change. The legal arguments in previous rounds of litigation over the ACA may have been weak, but they were not frivolous. This case is different; it's an exercise of raw judicial activism. Don't for a moment mistake it for the rule of law.” [The Washington Post]

>> Hadley Heath Manning, policy director, Independent Women's Forum: “Judge O'Connor's ruling is common sense: The individual mandate cannot be a proper use of Congress's taxing power now that there is no tax penalty for going uninsured. Americans should celebrate this decision and welcome the advancement of this case to the appellate level and then the Supreme Court. … This case should encourage lawmakers on both sides of the aisle to consider a radically different approach centered not on government rules but on patient choice and high quality care for all.”

>> Marty Lederman, visiting associate professor, Georgetown University Law Center: “Severability's the least of it—it's indefensible on the merits, too, because there isn't any 'mandate' to maintain health insurance. Oh, and BTW, O'Connor didn't enjoin anything, let alone 'strike down' the ACA.” [Twitter]

>> Josh Blackman, South Texas College of Law and author of two books about the Affordable Care Act: “Judge O'Connor was correct to find that the individual mandate can no longer be saved. However, I part company on the second part. The court should have only set aside the mandate, as well as the guaranteed issue and community rating. The remainder of the ACA can be severed. … His constitutional analysis concerning the mandate was supported by a majority of the Supreme Court. … Judge O'Connor's ultimate conclusion on severability—that the entire ACA must fall if the mandate is unconstitutional—was supported by the NFIB joint dissenters. Judge O'Connor's sweeping ruling has the foundation of four votes on the Supreme Court. [The Volokh Conspiracy]

>> Ted Frank, Competitive Enterprise Institute: “Not a fan of ACA or King v. Burwell decision, and usually a fan of Texas, but this is an embarrassingly bad decision, and if a liberal judge had issued something like it goring a conservative ox, conservatives would be rightly up in arms.” [Twitter]

Read more:

• One side effect of the ACA? Fewer evictions.
• CMS has 'contingency plans' if ACA is overturned
• The dismantling of the ACA: A timeline