The Trump administration has officially asked SCOTUS to strike down the ACA. What comes next?

The final showdown over the fate of the Affordable Care Act (ACA) kicked off in earnest late Thursday, as the Trump administration filed its brief reaffirming its belief that the law was rendered unconstitutional by Congress in 2017.

The concept at the center of the debate is "severability."

The Department of Justice (DOJ), several red state attorneys general and two individual plaintiffs argue that Congress's decision to zero out the penalty for the ACA's individual mandate in 2017 strikes down the entire law, as that piece cannot be severed from its other provisions.

In its brief (PDF), the DOJ said there's no evidence that Congress intended the remainder of the ACA to continue without the mandate's penalty in place.

"The entire ACA thus must fall with the individual mandate, though the scope of relief entered in this case should be limited to provisions shown to injure the plaintiffs," the DOJ said.

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Blue states and the House of Representatives, which sued into intervene in the case, argue the opposite: If Congress had intended to eliminate the ACA in full, it would have done so in 2017.

Instead, it merely eliminated the mandate penalty while keeping the rest intact.

The Fifth Circuit Court of Appeals ruled in December that the individual mandate is unconstitutional now that its penalty has been eliminated but punted on the central severability debate, instead remanding the decision to a lower court.

A District Court judge in Texas ruled in late 2018 that nixing the mandate penalty rendered the entire law unconstitutional, a decision the Trump administration backed in March 2019 after initially declining to defend the ACA but not offering a further opinion.

What's next for the case?

While all the major parties have weighed in to the U.S. Supreme Court on where they stand, a final decision is still likely far afield.

The Court agreed to take up the case in March, setting up a likely timeline for oral arguments later this year. Analysts say a decision could come by the spring.

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The DOJ's brief leaves room for some elements of the ACA to remain even if SCOTUS strikes down the law, as it urges the court to eliminate just the penalties that harm the plaintiffs. The agency's lawyers have previously argued in support of keeping intact elements of the ACA that target fraud enforcement, for example.

However, University of Michigan law professor Nicholas Bagley, an expert on the case who backs the ACA, noted in a Twitter thread that it doesn't matter if the DOJ is okay with those elements of the law. Once it's gone, it's gone.

If the court renders the law unconstitutional, it will be unenforceable from top to bottom, he said.

"These statements from the Trump administration's brief are confusing a lot of people," he tweeted. "So let me clear: If the Supreme Court says that the entire ACA is inseverable from the mandate, there will be nothing left of it."

    What that means, in non-legalese, is that the federal government would immediately stop enforcing the ACA because of its respect for the judgment of a co-equal branch that, in our constitutional culture, has final say on these kinds of questions.
    — Nicholas Bagley (@nicholas_bagley) June 26, 2020

The case is likely to be the headliner ruling for the upcoming SCOTUS term.