As the Supreme Court has said time and again, no provision of a statute should be read in isolation. Laws must be read as a whole, with an eye to harmonizing their interdependent parts. That means the court is reluctant to read a stray passage here or there in a way that would destabilize an entire statutory scheme.

The plaintiffs, ignoring that cardinal principle, instead base their argument on snippets of text in a statutory provision that the Affordable Care Act added to the tax code. That provision, which addresses the tax credits that poor and working-class people can use to help pay for a health plan, links the size of those credits to the cost of a plan bought “through an exchange established by the state.” According to the plaintiffs, those seven words represent a congressional threat to the states: Either set up exchanges or lose billions of dollars in tax credits.

But would Congress really have issued a threat of this magnitude in such a backhanded way? When Vito Corleone in “The Godfather” made a man an offer “he couldn’t refuse,” he wasn’t subtle about it: “Either his brains or his signature would be on the contract.” That’s how you threaten somebody. The phrase “through an exchange established by the state” doesn’t cut it.

The states had no reason to suspect that Congress would threaten them by inserting an innocuous phrase into a technical provision of the tax code. Instead, the states properly focused their attention on parts of the statute that detailed the consequences for refusing to establish an exchange. That would have been the natural place for Congress to level a threat at the states.

But not only did Congress issue no threat, it also offered protection. Because Congress understood that some states might refuse to establish exchanges, it included a fallback: The federal government would step in and run the exchange on the state’s behalf.