Obamacare opponents have a new approach to attacking the law — incoherence.

On Friday, a federal judge in Texas accepted the argument of 20 Republican attorney generals that the ACA’s mandate requiring everyone to have insurance is unconstitutional because the tax penalty enforcing it has been repealed. In other words, he struck it down because it no longer has any practical effect. Logic was in for a rough ride in this decision. (To read the full opinion, click here.)

Judge Reed O’Connor relied on the Supreme Court’s 2012 ruling that the mandate’s penalty is constitutional as a tax on those who choose to remain uninsured. But, as part of the 2017 tax bill, Republicans voted to set the amount of the tax at zero. O’Connor concluded that the mandate and the tax penalty are separate, so if the mandate stands on its own and doesn’t trigger the tax, it has lost its constitutional foundation.

But without the tax, the mandate doesn’t trigger anything. It persists as a directive that everyone have health insurance (with a few exceptions) but with no penalty for failing to comply. It has become a “mandate” in name only.

Why bother arguing about a now meaningless provision in a much larger law? Because it gave O’Connor a pretext to strike down everything else in the law. He claimed that the mandate, even in its denuded form, remains central to the ACA’s entire legislative scheme — not just to the provisions regulating insurance markets to which it directly relates, but to everything. In legal terms, he found that it is not severable.

Whether a single provision that is struck down by a court can be severed from the law that contains it is a decision for Congress to make when is enacts legislation. In this case, Congress spoke loud and clear. It repealed the mandate penalty as part of the 2017 tax bill after considering numerous proposals to repeal everything else and enacting none of them. If Congress found the mandate to be as central as O’Connor claims, why would it have approved a proposal to repeal it in isolation?

The consequences of this bizarre ruling could be devastating. If the entire ACA were to fall, millions of people who obtain coverage through the exchanges would lose it, and those with preexisting medical conditions might never be able to get it back. Millions more who gained coverage through the expansion of Medicaid would lose coverage, as well.

But that is just the start. The ACA contains hundreds of provisions that have nothing to do with insurance and affect almost every other aspect of the health-care system. As a few examples, it enables drug companies to develop and market generic copies of expensive biotechnology drugs known as biosimilars; it rewards hospitals and physicians for forming accountable care organizations that coordinate care to improve efficiency and quality; it improves Medicare drug coverage; and it implements numerous prevention initiatives, like calorie counts on chain restaurant menus.

By what contortion of logic could the mandate, even if it still had practical effect, be considered central to provisions like these? Clearly, Congress didn’t think so.

Fortunately, the chaos that would accompany full ACA invalidation is not imminent. O’Connor’s decision will be appealed, and he declined to issue an injunction, at least for now, against enforcement of the law while those proceedings are pending. The Trump administration has said that it considers the law still to be in effect.

Ultimately, the appeals will likely reach the Supreme Court, which has upheld the ACA twice before. This time, it will have to decide whether a mandate that has been rendered meaningless can be unconstitutional and whether completely unrelated provisions of the law that contains it should be struck down against the clear intent of Congress.

These are issues more suited to Alice in Wonderland than a legitimate lawsuit. The latest case against Obamacare is not just an assault on American health care. It is an assault on logic.

Robert I. Field is professor of law and public health at Drexel University and is the founder and editor of the Health Cents blog on Philly.com.