The Supreme Court on Thursday upheld the scope of a federal sex offender registration law.

The 2006 Sex Offender Registration and Notification Act requires sex offenders to register with the National Sex offender registry and update their registration when they travel or move.

Thursday’s 5-3 opinion turns away an effort to revive the “non-delegation doctrine” of the Constitution — a legal theory that holds that Congress can’t delegate its legislative power to other branches without giving the proper guidance.

Some conservatives hope to use the principle to cut back on the power of federal agencies.

A Maryland man, Herman Gundy, argued that Congress had unlawfully left it up to the attorney general to determine the law’s application as it applies to those who were convicted before its enactment.

The court disagreed in this case, saying that Congress had properly transferred its power to another branch of government when it passed the law.

“Indeed, if SORNA’s delegation is unconstitutional, then most of Government is unconstitutional — dependent as Congress is on the need to give discretion to executive officials to implement its programs,” Justice Elena Kagan wrote in the majority opinion.

Gundy pled guilty to sexual assault with a minor in Maryland in 2005, before the enactment of SORNA. After his release in 2012, he failed to register in New York and was subsequently charged with violating the law.

He challenged his indictment, arguing in part that Congress had delegated too much power to the Attorney General — to determine how the law applies retroactively — in violation of the “nondelegation” doctrine of the Constitution.

The Trump administration argued in favor of the federal law, saying Congress was not delegating its authority, but merely giving the attorney general guidance on how to apply the law, because it knew that there would be practical issues for the executive branch to address.

Only eight justices heard the case because it was argued before Justice Brett Kavanaugh took the bench.

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“Although the Court did not revisit the nondelegation doctrine in today’s ruling, all four of the conservative Justices who participated suggested that they have concerns with that principle, and want to revisit it in a future case,” said Steve Vladeck, CNN Supreme Court analyst and professor at the University of Texas School of Law.

Vladeck said that Justice Samuel Alito’s concurring opinion and Justice Neil Gorsuch’s dissent “strongly suggest that, in a future case in which Kavanaugh can participate, there may well be five votes to fundamentally reconsider Congress’s constitutional authority to delegate legislative and judicial power to administrative agencies.”