Although the decision in the affirmative action case, Fisher v. University of Texas, is getting the most press, another of today’s opinions, United States v. Kebodeaux, is also of interest.

In 1999, Anthony Kebodeaux was sentenced to three years in prison for statutory rape. He served his time and was freed. Years later, when Kebodeaux moved intrastate from San Antonio, Texas to El Paso, Texas, he failed to update his change of address within the three-day period as required by the federal Sex Offender Registration and Notification Act (SORNA) of 2006.

Because Kebodeaux was freed from federal custody, the Fifth Circuit ruled that his “unconditional” release meant that Congress had lost jurisdiction over him and that they could not regain it without some action (such as interstate travel) that brought him back into federal jurisdiction. We filed a brief arguing that to allow Congress to assert jurisdiction over someone because he was once in federal jurisdiction would be improper because it would give Congress nearly limitless power. After all, all of us have been in federal jurisdiction at some point. This would be the “Hotel California” theory of jurisdiction: you can check out, but you can never leave.

In today’s opinion, however, Justice Stephen Breyer, writing for Justices Kennedy, Ginsburg, Sotomayor, and Kagan, tactfully sidestepped the “Hotel California” theory by holding that Kebodeaux had never actually checked out of federal jurisdiction, thus repudiating that Fifth Circuit’s characterization of Kebodeaux’s release as “unconditional.” The Court accepted the Solicitor General’s argument that, “through a complex set of statutory cross-references,” Kebodeaux was subject to another registration requirement, the Wetterling Act, at the time of his release. SORNA was merely a modification of the registration requirements of the Wetterling Act.

For reasons pointed out by Justice Clarence Thomas, this is incorrect as a matter of constitutional interpretation. The crucial textual provision here, as it so often is, is the Necessary and Proper Clause, and the central question is whether the SORNA is necessary and proper to “carrying into execution” an enumerated power of Congress. According to Justice Breyer, both SORNA and the Wetterling Act are necessary and proper extensions of Congress’s power to regulate the armed forces (Kebodeaux was convicted in a military court). Yet Breyer never explains how a sex-offender registry is both necessary and proper to Congress’s regulation of the armed forces. “Instead,” writes Thomas, “the Court explains how SORNA and the Wetterling Act serve various ends that are not enumerated in the Constitution,” such as protecting public safety.

Breyer writes at length about the social benefit of sex-offender registry laws, and his excursion into this “protecting the public safety” rationale caused Chief Justice John Roberts to write separately.

Roberts’s opinion is the most fascinating part of this case. Breyer’s discussion of the benefits of sex-offender registries is very, well, Breyer-esque, and Roberts wants to distance himself from any implications that the purported social benefits of sex-offender registries has anything to do with the Court’s holding. He agrees with the majority that Kebodeaux was always under Congress’s jurisdiction, but he doesn’t believe public safety has anything to do with the constitutional question. “Public safety benefits,” the Chief Justice writes, “are neither necessary nor sufficient to a proper exercise of the power to regulate the military.” He is correct.

Roberts wrote separately because he worries “that incautious readers will think they have found in a majority opinion something they would not find in either the Constitution or any prior decision of ours: a federal police power.” The “police power” is traditionally thought to be power over the “health, safety, welfare, and morals” of the people, and it has always been thought to reside only in the states, despite whatever encroachments the federal government has made into that area over the last century.

Roberts’s opinion will be worth quoting in future challenges to federal laws that encroach on state power. As we argued in our brief, the perpetual regulation of a person because he was once in federal jurisdiction is a “great substantive and independent power” (in the words of Chief Justice John Marshall) that cannot arise through incidental connections to an enumerated power. As Roberts writes: “It is difficult to imagine a clearer example of such a ‘great substantive and independent power’ than the power to ‘help protect the public … and alleviate public safety concerns.’” (Quoting Breyer’s majority opinion.)

Roberts then endorses, although not explicitly, the argument offered in our brief:

It makes no difference that the Federal Government would be policing people previously convicted of a federal crime–even a federal sex crime. The fact of a prior federal conviction, by itself, does not give Congress a freestanding, independent, and perpetual interest in protecting the public from the convict’s purely intrastate conduct.

Although a correct interpretation of the Necessary and Proper clause, such as the one offered by Justice Thomas, would strip Congress of the power to set up sex-offender registries at all, the majority opinion is not as bad as it could have been because it doesn’t provide a clear basis for expanding Congress’s jurisdiction in a limitless fashion. A silver lining for defenders of limited government, but not of much solace to Mr. Kebodeaux.