[slightly updated for clarification and to account for testimony during the hearing]

The Secretary of Defense is testifying at a HASC hearing beginning now.  Here are his prepared remarks.  As for the NDAA’s 30-day notice requirement, there is an implicit suggestion that perhaps the object of the law was satisfied by earlier briefings to Congress (“what we did was consistent with previous congressional briefings this administration provided in late 2011 and early 2012, reflecting our intent to conduct a transfer of this nature with these particular five individuals”).  Otherwise, the SecDef’s justification for not giving 30 days’ notice appears to be that there was an “exceptional circumstance” here–namely, that the deal would have been impossible with such notice:  “[T]his was not simply a detainee transfer, but a military operation with very high risk and a very short window of opportunity that we didn’t want to jeopardize – both for the sake of Sergeant Bergdahl, and our operators in the field who put themselves at great risk to secure his return.”  The Secretary explains that the deal with the Qataris was concluded on May 27th, and that by necessity events happened quickly after that:

[W]e grew increasingly concerned that any delay, or any leaks, could derail the deal and further endanger Sergeant Bergdahl.  We were told by the Qataris that a leak would end the negotiations for Bergdahl’s release.  We also knew that he would be extremely vulnerable during any movement, and our military personnel conducting the hand-off would be exposed to a possible ambush or other deadly scenarios in very dangerous territory.  And we had been given no information on where the hand-off would occur.

For all these reasons and more, the exchange needed to take place quickly, efficiently, and quietly.  We believed this exchange was our last, best opportunity to free him.

After the exchange was set in motion, only 96 hours passed before Sergeant Bergdahl was in our hands.  Throughout this period, there was great uncertainty about whether the deal would go forward.  We did not know the general area of the hand-off until twenty-four hours before.  We did not know the precise location until one hour before.  And we did not know until the moment Sergeant Bergdahl was handed over safely to U.S. Special Operations Forces that the Taliban would hold up their end of the deal.  So it wasn’t until we recovered Bergdahl on May 31st that we moved ahead with the transfer of the five Guantanamo detainees.

What the Secretary does not say directly, but what is implicit, is that a delay of 30 days for the transfer of the detainees after the recovery of Sergeant Bergdahl would have violated an agreement that the President had already concluded on behalf of the United States with Qatar.

The Secretary does not explain directly — not in his prepared remarks, anyway — why that understandable course of action makes the failure to satisfy the 30-day notice requirement legal; but the theory appears to be one of impossibility–not in the sense that such notice would have been literally impossible, but in the sense that it would have been impossible to make this deal to repatriate Bergdahl and also comply with the 30-day rule.

[UPDATE:  In the written statement there is no suggestion of a constitutional override.  In response to questions, by contrast, DOD General Counsel Stephen Preston testified that although the statute is facially constitutional, and although they do not believe the President may disregard it in any “emergent situation,” they have also concluded that application of the law in these “highly unusual circumstances” would unduly interfere with the President’s constitutional authority to make efforts necessary to repatriate members of U.S. armed forces . . . thereby suggesting a discrete, cabined form of as-applied constitutional override, triggered not by a general Commander-in-Chief authority, but instead by an authority to take steps to save American service members overseas.  See, e.g., the video at approximately 2:03-2:05 and 2:18 to 2:23.]

One other thing of note about the Secretary’s remarks, concerning the five Taliban detainees:  They have commonly been described in public accounts as very dangerous “terrorists,” even though the publicly available facts about them suggest that the picture may not be as unequivocal as that.   [CLARIFICATION:  I do not mean to be suggesting any conclusion or knowledge about the risk these individuals pose–merely that we lack enough facts to make any reliable assessment.]  The Secretary notably does not describe the five former detainees as “terrorists,” or as presenting any threat to the United States different from that posed by officers of other enemy forces that the U.S. or other nations have often captured in armed conflicts.  (And the U.S.’s armed conflict with the Taliban presumably is coming to an end before these detainees are able to leave Qatar.)  Instead, the Secretary writes that the detainees “have not been implicated in any attacks against the United States, and we had no basis to prosecute them in a federal court or military commission.  It was appropriate to consider them for an exchange.”  [UPDATE:  As Ryan notes, later in the hearing the Secretary read from an assessment written by the Director of National Intelligence that even if these five detainees returned to Afghanistan or Pakistan after a year, “a few new Taliban leaders, no matter how senior” their position, “will not appreciably change the threat to the Afghan people, to the Afghan army, or, most importantly for us, to our forces.”  See approximately minutes 6 to 9 of the second part of the video.]