The Hague Convention on Civil Aspects of International Child Abduction* is intended to permit speedy resolution of disputes as to which nation is the appropriate place to resolve child custody disputes, by assuring return of the child(ren) to their "habitual residence", except under extraordinary circumstances. While generally the problem with Hague proceedings is that they are not speedy enough, sometimes they may be too speedy.
Last week, the U.S. Supreme Court heard argument in Chafin v. Chafin, to address the issue.
While it's not as headline-worthy as the DOMA cases, for the increasing number of parents with international, and intercontinental child custody arrangements, it may be more critical.
*I note the full title, because any treaty between nations signed at the Hague will be titled as a "Hague Convention", and simply searching those two words may end you up, for example, at the Hague Convention on the Launching of Explosives From Balloons.