According to the Wall Street Journal, the President's people are "drafting options" to bring about Guantanamo's closure, an objective that would require the White House to get around a statutory restriction on transferring GTMO detainees to the United States. Or not: Vice's Jason Leopold reports that NSC Spokeswoman Caitlin Hayden today said the Administration does not know what "'new press reports are referring to when they say the Administration is 'drafting options' intended to 'override a congressional ban.'" At any rate---and to the extent there really is a policy change under consideration---there are two choices. One option would be to veto annual legislation which presumably will renew the domestic transfer ban, the National Defense Authorization Act ("NDAA"). But there's another possibility in play, too, according to the Journal's Jess Bravin and Carol Lee:
A second option would be for Mr. Obama to sign the bill while declaring restrictions on the transfer of Guantanamo prisoners an infringement of his powers as commander in chief, as he has done previously. Presidents of both parties have used such signing statements to clarify their understanding of legislative measures or put Congress on notice that they wouldn’t comply with provisions they consider infringements of executive power.
Put aside the chances--good or bad or zero--that President Obama actually ever would sign legislation renewing the no-U.S.-transfer ban, while also proclaiming that he won't enforce the ban for Commander-in-Chief reasons. Suppose he takes that approach. How would the move square with recent practice? (So as to avoid any doubt, I ask as someone who, as a policy matter, would love to see the prison shuttered posthaste.)
So far as I am aware---and I welcome correction---signing statements in fact have not claimed that funding restrictions for transfers to the United States are generally unconstitutional, or would implicate the President's authority as Commander-in-Chief specifically. On the other hand, the Administration explicitly has cited potential conflicts with that very authority, with respect to the NDAA 2013's provisions concerning the detention facility at Parwan, and still earlier, with respect to the NDAA 2012's requirement of military detention for certain persons. On the former the President said legislative restrictions regarding Afghan detainees "could interfere with my ability as Commander in Chief to make time-sensitive determinations about the appropriate disposition of detainees in an active area of hostilities." On the latter, the President said the Administration would implement the NDAA 2012's mandatory military detention language through procedures designed to ensure flexibility---and that the President would "exercise all of my constitutional authorities as Chief Executive and Commander in Chief if those procedures fall short."
Contrast this with the Administration's consistent claim regarding the no-transfer-to-the-U.S. regime---that it would, under certain circumstances, pose unspecified separation of powers problems and hinder criminal prosecutions. The below language comes from the President's signing statement for the NDAA 2014 (itself similar to statements issued upon signing of 2013 and 2012 bills):
In contrast, sections 1033 and 1034 continue unwise funding restrictions that curtail options available to the executive branch. Section 1033 renews the bar against using appropriated funds to construct or modify any facility in the United States, its territories, or possessions to house any Guantanamo detainee in the custody or under the control of the Department of Defense unless authorized by the Congress. Section 1034 renews the bar against using appropriated funds to transfer Guantanamo detainees into the United States for any purpose. I oppose these provisions, as I have in years past, and will continue to work with the Congress to remove these restrictions. The executive branch must have the authority to determine when and where to prosecute Guantanamo detainees, based on the facts and circumstances of each case and our national security interests. For decades, Republican and Democratic administrations have successfully prosecuted hundreds of terrorists in Federal court. Those prosecutions are a legitimate, effective, and powerful tool in our efforts to protect the Nation. Removing that tool from the executive branch does not serve our national security interests. Moreover, section 1034 would, under certain circumstances, violate constitutional separation of powers principles....In the event that the restrictions on the transfer of Guantanamo detainees in sections 1034 and 1035 operate in a manner that violates constitutional separation of powers principles, my Administration will implement them in a manner that avoids the constitutional conflict.
With all this as background, here's an observation about recent practice and a still-hypothetical, Commander-in-Chief power objection to the NDAA's prohibition on stateside transfers: it would sweep much more broadly than the Administration's prior claim that, in particular cases, the prohibition might violate the separation of powers or muck up forum selection in criminal cases. (Indeed, the very point of a more categorical constitutional objection would be to enable the Administration to bring legacy detainees---ones the government can't prosecute, but won't release in the short term---to the mainland.) For that reason, such an objection would also carry somewhat less persuasive force. You would think a serious threat to the Commander in Chief power would draw explicit comment from the executive branch at the time. And indeed, that is exactly what happened vis-à-vis other provisions of NDAAs in recent years, but what didn't happen vis-à-vis provisions establishing the inbound transfer ban.
The merits of a maybe-brewing, maybe-not Commander-in-Chief claim can be debated; some folks might buy it, some folks not at all. Right or wrong legally though, a claim of preclusive presidential power would seem to come a bit late in the game, given the executive branch's recent signing statement language.