[JURIST] The US Supreme Court [official website; JURIST news archive] heard oral arguments [day call, PDF; merit briefs] Tuesday in two cases. In United States v. Comstock [oral arguments transcript, PDF; JURIST report], the Court heard arguments on whether Congress had the authority to enact certain provisions of the Adam Walsh Child Protection and Safety Act [18 USC § 4248 text], which allow a person deemed "sexually dangerous" to be civilly committed after the expiration of a federal criminal sentence. The US Court of Appeals for the Fourth Circuit found [opinion, PDF; JURIST report] that the law was beyond Congress' authority under the Commerce Clause [Cornell LII backgrounder]. US Solicitor General Elena Kagan [official profile] defended the law, arguing:

What Congress said here was something pretty simple and very reasonable. It said if we, the Federal Government, have somebody in our custody, and we know that that person has the kind of mental illness that is going to cause grave danger to the community; and we know that there is no one else who is in a good position to prevent it; and we know that we were in part responsible for that vacuum, then we should be able to do something about it. That's what section 4248 says, and section 4248 is constitutional for that reason.

The Hague Convention exists to ensure that custody disputes are resolved by the courts of the country of habitual residence rather than through abduction. It thus generally requires the return of a child who is abducted in violation of a right of custody. So too, a ne exeat right permits a parent to require that the child reside in the country of habitual residence, thereby rendering international abduction illegal.

Ne exeat rights are not only rights of custody under the text of the convention, but they also track the convention's vital purpose of ensuring that children are not subject to international abduction.