Halbig is about determining whether the president, like an autocrat, can levy taxes on his own

The president’s defenders often concede that he is doing the opposite of what federal law says. Yet he claims that he is merely implementing the law as Congress intended.

Such claims should be met with more than the usual skepticism when made by a president who openly advocates unilateral action—”I’ve got a pen, and I’ve got a phone”—when the legislative process doesn’t produce the result he wants, and when they are made by a president whose expansive view of his powers the Supreme Court has unanimously rejected 13 times. Unfortunately, the abuse of power exposed in Halbig may trump them all.

Here’s where the president broke bad. The Patient Protection and Affordable Care Act directs states to establish “exchanges” to regulate the sale of health insurance. If a state declines to do so, as 36 states have, the health-care law directs the federal government to “establish and operate such Exchange within the State.” But here’s the rub: Certain taxpayers can receive subsidized coverage, the law says, if they enroll “through an Exchange established by the State.” The law nowhere authorizes subsidies through exchanges established by the federal government.