This time, he’s serious. After all these years of unexecuted veto threats, on October 22, 2015, President Obama finally vetoed the $612 billion National Defense and Authorization Act, in part because of its restrictions on his ability to close Guantánamo before the end of his presidency. As the New York Times noted, it was only the President’s fifth veto since taking office nearly seven years ago. And as Marty Lederman has noted here, in issuing the veto, the President questioned the bill’s restrictions on the President’s ability to move Guantánamo detainees:

I have repeatedly called upon the Congress to work with my Administration to close the detention facility at Guantanamo Bay, Cuba, and explained why it is imperative that we do so. As I have noted, the continued operation of this facility weakens our national security by draining resources, damaging our relationships with key allies and partners, and emboldening violent extremists. Yet in addition to failing to remove unwarranted restrictions on the transfer of detainees, this bill seeks to impose more onerous ones. The executive branch must have the flexibility, with regard to those detainees who remain at Guantanamo, to determine when and where to prosecute them, based on the facts and circumstances of each case and our national security interests, and when and where to transfer them consistent with our national security and our humane treatment policy. Rather than taking steps to bring this chapter of our history to a close, as I have repeatedly called upon the Congress to do, this bill aims to extend it. …

So what’s next? The game is not over, it’s just beginning. The New York Times quotes Charles M. Cameron, a politics professor at Princeton, saying:

“This is a very, very unusual use of the veto.” “Typically vetoes either kill bills or force Congress to compromise on the content of the bill,” but in this case, he said, “the president wants a compromise on an entirely different bill.”

So now begins a dialectic process between the White House and Congress to determine the fate of the NDAA, which unlike the defense appropriations bill — one of 12 appropriations bills that actually appropriates government funds — sets policies and spending levels for the military. In both the upcoming authorization and appropriations negotiations, a key player will now almost surely be the new Speaker-apparent, former Vice Presidential candidate Paul Ryan.

But what would the content of a final NDAA look like? As news accounts make clear, the core of the administration’s concern with the NDAA is not just the Guantánamo provisions, but also the strict spending limits on military and domestic programs enacted in the 2011 Budget Control Act, to which Secretary of Defense Ashton Carter has repeatedly objected. As the President’s veto statement indicates: The vetoed bill “underfunds our military in the base budget, and instead relies on an irresponsible budget gimmick that has been criticized by members of both parties.” Suppose that over the next few months of negotiations, these funding disputes can be worked out between Congress and the White House, but Congress refuses to budge on the Guantánamo provisions?

Could the President sign a revised NDAA, yet argue that the Guantánamo funding restrictions are unconstitutional? If you look back at the President’s veto statement above, you will see that this time, he invoked a policy rationale, not a constitutional one, in challenging the Guantánamo provisions (emphasis added):

[I]n addition to failing to remove unwarranted restrictions on the transfer of detainees, this bill seeks to impose more onerous ones. The executive branch must have the flexibility, with regard to those detainees who remain at Guantanamo, to determine when and where to prosecute them, based on the facts and circumstances of each case and our national security interests, and when and where to transfer them consistent with our national security and our humane treatment policy.

But are these “more onerous” restrictions not just bad policy, but actually unconstitutional? Note the similarity between how the President’s veto statement describes the GTMO restrictions, and this paragraph in a speech I gave in Oxford in May 2013 (emphasis added):

Starting in 2010, Congress has used authorization bills to impose a series of counterproductive restrictions on the transfer of Guantánamo prisoners. But some of those restrictions are subject to waiver requirements and all must be construed in light of the President’s authority as commander-in-chief to regulate the movement of law-of-war detainees, as diplomat-in-chief to arrange diplomatic transfers, and as prosecutor-in-chief to determine who should be prosecuted and where. If Congress insists on passing such onerous and arguably unconstitutional conditions in the next National Defense Authorization Act, the President should call its bluff and forthrightly veto that legislation.

Of course, Congress enjoys the power of the purse, but could the President challenge an authorization or appropriations bill containing such provisions as violating the Constitution? In response, could Congress charge that the President was trying to gut a core congressional prerogative? Such a debate would take us into largely uncharted constitutional territory: When, exactly, do authorization and appropriations bills become unconstitutional?

There is surprisingly little teaching on this subject. As David Barron and Marty Lederman acknowledged a few years ago, “the Appropriations Clause does not explain which expenditure conditions on presidential wartime powers are constitutionally permissible and which are not.” Plainly, Congress may not use its appropriations power to “make [a] law” restricting the freedom of speech or of the press. Nor, presumably, could it use that power to violate any other provision of the Bill of Rights — e.g., to violate due process or enforce a cruel or unusual punishment.

Nearly half a century ago, in United States v. Lovett, the Supreme Court struck down as unconstitutional a bill of attainder provision in an appropriations act that barred the payment of salaries to named federal employees. By so saying, the Court held that Congress could not use its appropriations power to require the President to punish particular individuals by legislation, in violation of the Bill of Attainder Clause, a textual prohibition in the Constitution. Justice Black wrote that “[t]he section’s language as well as the circumstances of its passage … show that … [the law] was designed to force the employing agencies to discharge respondents and to bar their being hired by any other governmental agency.” But significantly, the Lovett Court rejected the proposition that the exercise of appropriations power is “plenary and not subject to judicial review” and suggested that budgetary action designed to punish certain individuals is just as much a violation of the Bill of Attainder Clause as if Congress had passed a law declaring those individuals guilty of a crime.

But when does an appropriations or authorization bill violate the separation of powers? This issue has rarely come before the courts. During the Iran-Contra Affair, the Reagan administration argued unpersuasively that the Boland Amendment violated the President’s plenary foreign affairs powers. More than a quarter century ago, in Federal Employees v. United States, an opinion later vacated by the Supreme Court, a federal district court further declared that “By [an appropriations] measure, Congress cannot accomplish that which by direct legislative action would be beyond its constitutional authority.” A year later, I argued in The National Security Constitution (at page 130) that these precedents leave “the President free to challenge future limitations on executive branch actions as unconstitutional exercises of Congress’s power of the purse.”

Since then, the Justice Department’s Office of Legal Counsel (OLC) has on several occasions advised that as “[b]road as the spending power of the legislative branch undoubtedly is, it is clear that Congress may not deploy it to accomplish unconstitutional ends.” But exactly what would constitute such “unconstitutional ends?”

Presumably, Congress could not use its spending power to require a court to decide a case in only one way. Neither could it use appropriations to nullify the President’s exercise of one of his textual Article II powers, such as the veto or the power to pardon. Even where Article II’s textual hook is less explicit, appropriations limitations presumably should not bar the President from exercising core Article II functions.

Since the Iran-Contra Affair, OLC has deemed several restrictions that infringe upon the President’s exercise of his authorities as Chief Executive to be unconstitutional infringements upon the separation of powers. For example, in February 1990, Deputy Attorney General Bruce Navarro conveyed to Richard Darman, Director of the Office of Management and Budget, OLC’s view that a provision of Foreign Relations Authorization Act, Fiscal Years 1990 and 1991, that limited the President’s ability to receive spies as ambassadors was unconstitutional, even though the President could waive the limitation if it were in the national security interests of the United States to do so. Six years later, then-head of OLC Walter Dellinger wrote to then-State Department Legal Adviser Conrad Harper finding that a legislative provision requiring the President to make a detailed certification before using appropriated funds to expand the United States’ diplomatic presence in Vietnam constituted “an unconstitutional condition on the exercise of the President’s” recognition power. Five years after that, OLC wrote again, opining that an appropriations restriction was unconstitutional, because it would unconstitutionally infringe on the President’s decision regarding “whether and how [US forces] are to cooperate with foreign or international forces in the same theater of operations.” And on June 1, 2009, the Acting Head of OLC, (now federal judge) David Barron, opined that the State Department could disregard Section 7054 of the Fiscal Year 2009 Department of State, Foreign Operations, and Related Programs Appropriations Act, which purported to prohibit all funds made available under title I of that act from being used to pay the expenses for any United States delegation to a specialized UN agency, body, or commission that is chaired or presided over by a country with a government that the Secretary of State had determined supports international terrorism, because. OLC reasoned that “the provision unconstitutionally infringed on the President’s authority to conduct the Nation’s diplomacy.” President Obama invoked a similar rationale recently in avoiding NDAA restrictions to secure the release of Taliban prisoner Bowe Bergdahl, and Congress did essentially nothing thereafter to protect its claimed constitutional prerogative over the power of the purse.

All of which raises the question: When, exactly, does the President engage legitimately in what David Pozen calls “constitutional self-help?” And when, on the other hand, does the President’s claim of authority to use force unfettered by congressional restrictions become unconstitutional, because it effectively nullifies the Declare War Clause and/or undermines Congress’ core power of the purse?

In short, as the late, great Yogi Berra liked to say, it’s déjà vu all over again. The George W. Bush administration became famous for its signing statements. If the Obama administration is finally serious about closing Guantánamo, the next year may see a presidential signing statement on a revised NDAA indicating non-acquiescence going forward with the embedded congressional restrictions on Guantánamo directives. If the President then brought Guantánamo detainees off the island, the ball would be in Congress’ court to enforce its own NDAA restrictions. If enough members of Congress cared to secure congressional standing, they could bring the issue to a head in court. But most likely, the President’s action would stand even if challenged, as Prosecutor-in-Chief to “determine when and where to prosecute them, based on the facts and circumstances of each case and our national security interests,” and as Diplomat-in-Chief and Commander-in-Chief to decide and arrange through negotiations “when and where to transfer them consistent with our national security and our humane treatment policy.” This would create the legal space for President Obama to leave office, finally having fulfilled his most vexing campaign promise: to close Guantánamo.