Several excellent posts challenge the legality of the President's exchange of five Taliban prisoners held at Guantanamo for a U.S. soldier held by the Taliban -- see Josh Blackman here, Ilya Somin here (toward the bottom of the post), and especially Tim Sandefur here.

As the posts explain, the exchange violated a U.S. statute that prohibits releasing any prisoners from Guantanamo without 30 days notice to Congress (which was not given here). But, is the statute constitutional? The President earlier indicated it is not (in a signing statement), and apparently that's his defense of the prisoner exchange. Blackman, Somin and Sandefur argue otherwise.

I think the President has a fairly strong case here. As I've argued previously, the President's commander-in-chief power indicates control of tactical aspects of military operations. I do not think that Congress could direct the President to defend a particular outpost against all odds rather than retreat, or mandate a frontal assault upon an enemy position. (Nor could Congress require the President to give 30 days notice prior to abandoning an outpost or making an attack). Here is an excerpt from my prior argument (citations omitted):

... Blackstone outlined two distinct military powers: one was legislative, encompassing the general regulation of the conduct of military personnel through "rules" such as the articles of war and other standing laws defining offenses and punishments; the other was executive, encompassing command and direction of the armed forces in response to specific circumstances. These categories line up with the two distinct powers the Articles [of Confederation] gave the Continental Congress: making rules for government and regulation (e.g., adopting the U.S. articles of war) and directing operations (e.g., telling Washington not to burn New York). Thus the Articles made clear that Congress had all the military power previously exercised by Britain: the government and regulation power associated with Parliament and the power of command associated with the king.

As has been widely recounted, the Articles’ Congress came under sharp and increasing criticism on structural grounds. It was unworkable in practice and indefensible in theory, critics said, because it combined executive and legislative power. Among other problems, the unwieldy multi-member Congress proved unable to manage executive tasks, including direction of the army. A large part of the constitutional project was to create separate legislative and executive branches and assign appropriate powers to each. This broader account makes it perfectly plausible—indeed, likely—that the Constitution’s framers had an idea of executive and legislative military powers that they wanted to assign to the President and Congress respectively.

Thus, the change in wording from the Articles to the Constitution is easily understood. Under the Articles, the executive and legislative military powers, though described separately, were exercised by the same branch, since there was only one branch. When the Constitution created the new Congress as a true legislative branch, naturally it gave Congress the legislative military powers, but not the executive ones. This change was accomplished by carrying over to Congress the Articles’ government-and-regulation power but not its directing-operations power.

The decision to release or exchange prisoners of war is similar. Like the decision to attack or retreat, it is part of the immediate management of the war effort -- the executive rather than legislative aspect of war. Thus I doubt Congress can use its "government and regulation" power to tell the President to exchange or not to exchange prisoners.

The present case is a little more difficult because the statute in question isn't a direct prohibition; rather it says that no money can be spent to effect a prisoner transfer to a foreign country except with the 30-day notice. Is that within Congress' spending power? It depends how much one thinks Congress can use its spending power to restrict executive power. On one hand, Congress likely has broad power to restrict spending at a strategic level (e.g., no funds to be spent for military operations in Vietnam) for the reasons Tim Sandefur explains in his post. But on the other, Congress can't use spending to take away core presidential powers. Congress could not have the power to prevent the President from spending money to veto a bill or issuing a pardon (else those powers would not really exist in the President). If one views the tactical direction of military operations as a core presidential power akin to the veto or the pardon, Congress should not be able to use the spending power to prohibit its exercise.

I doubt, therefore, that Congress should be able to prevent the President from spending money to, for example, retreat from a defensive position or to attack an enemy position by frontal assault. If exchanging prisoners of war during wartime is a similar tactical decision, similarly Congress should not be able to use the spending power to constrain the President's control of it.

At minimum, it seems that critics of the President must either accept that Congress can prevent the President from issuing pardons by denying him money for a pen, or else explain why making command decisions is different from issuing pardons.

(Aside: a problem for the President here is that he signed the bill in the first place. Presidents, I think, generally are obligated not to sign legislation they believe to be unconstitutional. But Will Baude argues otherwise, under circumstances that appear to apply to the present statute -- namely, when the unconstitutional provision was part of a larger, otherwise-constitutional and in the President's view beneficial statute.)