Neal Katyal, a law professor at Georgetown University, served as acting solicitor general of the United States.

President Trump’s decision to argue that the Supreme Court should scrap the Affordable Care Act in its entirety is not just terrible policy in the midst of a pandemic — it is legally indefensible and a gross violation of his constitutional duty to take care that the laws are faithfully executed.

On Wednesday, apparently overriding the concerns of Attorney General William P. Barr, the administration said it will argue that the entire law must fall because one small piece of it is unconstitutional — in legal language, that the problematic part of the law cannot be severed from the rest of it.

Everything about this position is legally wrong. Twice before, the Justice Department has defended the Affordable Care Act against legal attack. Both times, the Supreme Court upheld the act. In the latest challenge to the law, a case involving a challenge brought by Texas and other Republican-led states, the argument is even weaker.

The administration’s claim in the case, which is to be argued this fall, is this: Congress in 2017 modified the Affordable Care Act by eliminating the required payment from those who do not purchase health insurance, the so-called individual mandate. Because the penalty is no longer in place, the administration contends, the justification for the individual mandate — that it is a valid exercise of Congress’s taxing power — has been eroded.

Even if that were correct — it isn’t — it is ludicrous to claim that this supposed defect somehow dooms the entirety of the law. When courts find problems in particular provisions of a law, they leave the rest of the law in place unless it is evident that Congress would not have proceeded without the invalid portions.

The purpose of this rule of thumb is elemental: Federal courts should try to do as little damage as possible to Congress’s handiwork. Here, the very same Congress that eliminated the tax penalty left the rest of the Affordable Care Act in place — it rejected the GOP’s attempts to repeal the law.

How could a Congress that was unwilling to repeal the law have meant, by removing one individual provision, to undo its entire architecture, from protection for individuals with preexisting conditions to the creation of health-care marketplaces? Even scholars who argued against the Affordable Care Act during the Obama administration have savaged this position, with one National Review essay calling it “troubling, trivial, and absurd.”

Those are fitting adjectives. Here is one more: irresponsible. From administration to administration, the Justice Department is duty-bound, through the Office of the Solicitor General, to defend the laws duly enacted by Congress if there is a reasonable argument to be made. That is true even when the administration does not like the law at issue. Though there may be circumstances where the president and Justice Department make a good-faith determination that a position is truly not supportable under the Constitution, here there is not even a pretense that there are extraordinary circumstances to justify abandoning this practice. Defending the law would not intrude on executive authority. Abandoning it would not further congressional intent — it would trample on it. And it would undo a comprehensive, landmark law, based on a single, supposed legal error.

On one level, the administration’s decision to argue that the law should be struck down in its entirety was unsurprising. After initially arguing that the individual mandate penalty provision could be severed from the rest of the law, the Justice Department changed its position to argue for invalidating the statute in its entirety. Shifting its stance yet again would have been remarkable.

On another level, the fact that the Justice Department has endorsed this extreme position before the Supreme Court is shocking. Courts depend on the Justice Department in our adversarial system to marshal the best arguments, forged by decades of expertise, in defending federal laws. The affront to the rule of law is particularly deep here. Congress passed the Affordable Care Act after extensive debate. It later removed the individual mandate penalty but declined to repeal the rest of the law. Now the department is asking the court to do what it couldn’t accomplish in Congress. It’s hard to see a more open call for judicial activism than what Trump is asking the court to do.

There is no logical stopping point to the position that an administration can refuse to defend a law in court simply because it doesn’t like it. If the president can ask the Supreme Court to strike down this statute, this or a future administration can seek to do this for any law. Trump might seek to overturn the 1883 Pendleton Act, which created the modern civil service. A President Biden might go into court to get any law Trump signed into law thrown out. That’s not the way our system works.

Nine years ago, as acting solicitor general, I defended the Affordable Care Act from constitutional challenge in court, arguing in part that the law supplements the critical role the federal government plays in preventing diseases that rapidly spread across state borders, particularly in an age of modern travel. Little could I have imagined that my former office would join in an effort to dismantle a law that is providing health coverage to millions of Americans amid a devastating pandemic.

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