Excerpt from Justice Anthony Kennedy's concurrence, in which Chief Justice John Roberts and Justice John Paul Stevens joined:
Whatever the ultimate merits of the parties' mootness arguments, there are strong prudential considerations disfavoring the exercise of the Court's certiorari power. Even if the Court were to rule in Padilla's favor, his present custody status would be unaffected. Padilla is scheduled to be tried on criminal charges. Any consideration of what rights he might be able to assert if he were returned to military custody would be hypothetical, and to no effect, at this stage of the proceedings.Read the full text of the concurrence [PDF], and the full text of Justice Ruth Bader Ginsburg's dissent [PDF]. Reported in JURIST's Paper Chase here.
In light of the previous changes in his custody status and the fact that nearly four years have passed since he first was detained, Padilla, it must be acknowledged, has a continuing concern that his status might be altered again. That concern, however, can be addressed if the necessity arises....
That Padilla's claims raise fundamental issues respecting the separation of powers, including consideration of the role and function of the courts, also counsels against addressing those claims when the course of legal proceedings has made them, at least for now, hypothetical. This is especially true given that Padilla's current custody is part of the relief he sought, and that its lawfulness is uncontested.