The Supreme Court plays Six Degrees of Kevin Bacon.

Scalia's tangent focused on state laws that hold shippers liable for knowingly distributing tobacco products to minors (the New York settlement was a deal cut between New York, other states, and the shippers to resolve claims of rampant violations by shippers of these state laws). These laws apply the same restraints to FedEx drivers as to every other person or business that sells or distributes tobacco products—they are, in other words, a classic example of a law that applies across the board. But related to is a mighty broad concept. Scalia is right that, to some extent, these laws relate to the FedEx service of delivering tobacco products. But by the same token, states would be pre-empted from enforcing speeding or double-parking laws against FedEx delivery trucks. Just as surely, these laws also relate to FedEx services in Maine. That can't be what Congress intended.

That's the peril of playing the Kevin Bacon game in pre-emption cases. You start asking, "Isn't this also related?" and soon imperil important and popular state laws that Congress had no intention of pre-empting. Scalia himself recognized this a decade ago in another pre-emption case, when he stated that "applying the 'relate to' provision according to its terms was a project doomed to failure, since, as many a curbstone philosopher has observed, everything is related to everything else."

But recognizing the problem doesn't solve it. Related-to provisions give the court enormous discretion to uphold or strike down state laws. A justice's view of the wisdom of the state law inevitably colors this calculus. At the Rowe argument, Justice Scalia was openly contemptuous of the aggressive tactics used by Eliot Spitzer in combating youth tobacco use. Correspondingly, he and other conservatives on the court seemed eager to reach the conclusion that these tactics must be pre-empted.

Just about every member of the Supreme Court has at some point bemoaned Congress' abdication of guidance to the court in pre-emption cases. The question is whether the justices are ready to do something about it. Rowe and Riegel present an opportunity for the court to push back on Congress and demand that it state clearly the extent to which it wants to displace state law. (If Congress is not clear, the state law would stand.) In Riegel, there is no clear statement and no evidence that Congress intended to block the state remedies at issue.

Congress should welcome a clear rule from the court about clear statements. At judicial confirmation hearings, senators of both parties like to bemoan judges who they say take it upon themselves to make law. But by using legislative language that grants virtually unfettered discretion to the courts, Congress is not just inviting this lawmaking, it's requiring it.