[UPDATED]  The Pentagon has issued the following statement about the U.S.’s use of 59 Tomahawk missiles against the Shayrat Airfield in the Homs governorate of Syria this evening:

Statement from Pentagon Spokesman Capt. Jeff Davis on U.S. strike in Syria

At the direction of the president, U.S. forces conducted a cruise missile strike against a Syrian Air Force airfield today at about 8:40 p.m. EDT (4:40 a.m., April 7, in Syria). The strike targeted Shayrat Airfield in Homs governorate, and were in response to the Syrian government’s chemical weapons attack April 4 in Khan Sheikhoun, which killed and injured hundreds of innocent Syrian people, including women and children.

The strike was conducted using Tomahawk Land Attack Missiles (TLAMs) launched from the destroyers USS Porter and USS Ross in the Eastern Mediterranean Sea. A total of 59 TLAMs targeted aircraft, hardened aircraft shelters, petroleum and logistical storage, ammunition supply bunkers, air defense systems, and radars. As always, the U.S. took extraordinary measures to avoid civilian casualties and to comply with the Law of Armed Conflict. Every precaution was taken to execute this strike with minimal risk to personnel at the airfield.

The strike was a proportional response to Assad’s heinous act. Shayrat Airfield was used to store chemical weapons and Syrian air forces. The U.S. intelligence community assesses that aircraft from Shayrat conducted the chemical weapons attack on April 4. The strike was intended to deter the regime from using chemical weapons again.

Russian forces were notified in advance of the strike using the established deconfliction line. U.S. military planners took precautions to minimize risk to Russian or Syrian personnel located at the airfield.

We are assessing the results of the strike. Initial indications are that this strike has severely damaged or destroyed Syrian aircraft and support infrastructure and equipment at Shayrat Airfield, reducing the Syrian Government’s ability to deliver chemical weapons. The use of chemical weapons against innocent people will not be tolerated.

Notice that this statement did not include any argument about why the strikes are legal.  Neither did the President’s public statement this evening.  There are undoubtedly many questions associated with the operation that are more immediately significant than the question of whether the President has complied with the law–such as what the possible ramifications might be, and whether the attacks will do anything to deter Assad’s barbaric use of chemical weapons on civilians and others.  Yet the legal questions are of profound importance, too, and this is, after all, a law-related blog, so here goes . . . .

Let’s begin with international law.  As the Pentagon statement indicates (“the U.S. took extraordinary measures to avoid civilian casualties and to comply with the Law of Armed Conflict”), the United States initiated an armed conflict with Syria this evening–and therefore its actions are bound by the international laws of armed conflict.  There is no reason–not yet, anyway–to think that the United States has violated those laws.

Nevertheless, the operation raises jus ad bellum questions, wholly separate from the jus in bello.  Ryan is right that the strikes against Syria — done in the absence of a U.N. Security Council resolution, and without any apparent justification of self-defense (as the Pentagon explained, its function is to “deter the regime from using chemical weapons again,” presumably against Syrian nationals) — violate Article 2(4) of the United Nations Charter, which requires the U.S. and all other signatory states to “refrain in their international relations from the threat or use of force against the territorial integrity or political independence of any state.”  [I should note here that our friend and co-blogger Harold Koh has recently argued (see pp. 1004-1015 here) that certain humanitarian interventions–perhaps, but not necessarily, including President Trump’s actions this evening–would not violate Article 2(4) by virtue of an alleged developing new customary exception.  In my view, whatever the merits of such a rule of international law might be (and they are many), it cannot be established by custom in the teeth of a treaty prohibition.  The remainder of this post proceeds on the assumption that the strikes violate the Charter; but of course if Harold’s contrary view were correct, then the related constitutional question that I discuss below would, accordingly, become more complicated and uncertain.]

The obligation in Article 2(4) is not only international law, but also a treaty provision to which the U.S. is bound, and thus is the “supreme Law” of the land under Article VI of the U.S. Constitution.  It is, that is to say, a “domestic law” constraint, too.

Importantly, this does not mean that the Constitution forbids the United States from deliberately breaching a treaty.  To be sure, that’s not something the nation does very often, but there are historical examples where Congress has enacted a “later-in-time” statute that supersedes earlier treaty obligations as a matter of domestic law, and the Supreme Court has confirmed its constitutional authority to do so.  See, e.g., Whitney v. Robertson (1888); Chae Chan Ping v. U.S. (1889); Breard v. Greene (1998).  In such cases, any subsequent U.S. treaty breach may result in international-law sanctions, and also serious diplomatic and other ramifications for the nation–which is why Congress rarely chooses to authorize such breaches.  Nevertheless, Congress may decide to incur such costs in order to advance what it views as a more compelling objective.

In this case, however, Congress has not authorized the attacks on Syria, or otherwise made the solemn decision that the U.S. should breach the Charter.  Therefore, not only has President Trump put the U.S. in breach of its treaty obligations — in violation of his Article II obligation to take care that the treaty is faithfully executed — but he has also likely violated the constitutional allocation of war powers, too.

As I explained at length in this post back in 2013 (when President Obama was contemplating similar such strikes in response to Assad’s horrifying use of chemical weapons), there are three major schools of thought on the question of when the President can initiate the use of military force against another sovereign nation “unilaterally” (i.e., without congressional consent):

(i) almost never (i.e., only to repel actual attacks, and then only as long as Congress is unavailable to deliberate)–what one might call the “classical” position;

(ii) virtually always, up to and including full-scale, extended war–that was John Yoo’s position, adopted by OLC in the Bush Administration, at least in theory; and

(iii) only under a set of complex conditions that do not amount to “war in the constitutional sense,” and only in conformity with legal restrictions Congress has imposed (including the War Powers Resolution)–a middle-ground position that I denominated the Clinton/Obama “third way,” and which in effect has, rightly or wrongly, governed U.S. practice for the past several decades.

(I include below the slightly more detailed account I offered in 2013 of these three views of the constitutional framework.)

As I further explained back in 2013, however, whatever one’s views might be on the scope of the President’s authority to unilaterally use force abroad—whether you subscribe to the traditional restrictive view, the Bybee/Yoo permissive view, or the Clinton/Obama “third way” (or any variant in between)—there is no obvious justification for a unilateral presidential decision to cause the United States to violate a treaty that is binding as a matter of domestic law unless and until Congress passes a “later in time” statute permitting such a violation.  Under what authority can the President deliberately put the U.S. in breach of the U.N. Charter?*  (To invoke the register of the Clinton/Obama theory of war powers:  Because of its potentially profound impact on the practice of treaty compliance and the development of international law, and its possible severe consequences in terms of U.S. diplomatic relationships in light of the breach, such a use of force should be understood to be of a “nature” (and possibly a “scope” and “duration,” too) that constitutes a “war in the constitutional sense,” and therefore requires congressional authorization.)

This was, I think, the most troubling thing about the 1999 Kosovo operation, which was, at its outset, analogous in some respects to tonight’s missile strikes.  The Clinton Administration virtually conceded that the operation was in breach of the Charter.  To be sure, OLC concluded that Congress effectively authorized the Kosovo operation eight weeks after it began.  But why did President Clinton have the authority, without congressional authorization, to order the operation, and to breach Article 2(4), during those first eight weeks?  Just as Presidents Obama and Clinton were correct to assume that their unilateral uses of force (e.g., in Kosovo and Libya, respectively) were subject to the constraints of the War Powers Resolution, so, too, the President must act within the constraints of binding treaty obligations, absent congressional authority to do otherwise.

The Clinton Administration never did address this problem in connection with Kosovo; and, as Deborah Pearlstein explains, the use of force against Assad’s Syria is potentially even more problematic than the Kosovo campaign, because “it was done with no apparent international support – neither from our allies, nor from other countries in the region.”  This “glaring distinction from Kosovo” might mean that that Trump’s Syria operation will have much less international legitimacy than did the Kosovo operation, which occurred with vigorous NATO support and involvement.

In my view, this distinction ought to be very relevant for purposes of the constitutional question, because one of the principal reasons the framers required the assent of both political branches for war was to ensure a broad consensus, and solemn, interbranch deliberation, not only when American “blood and treasure” is put at risk, but also when the action in question threatens to undermine the nation’s international standing.  For that reason, in 2013 I agreed with my colleague and co-blogger David Cole (now legal director at the ACLU), that that President Obama’s decision to ask Congress for authorization for the use of force in Syria–and his decision not to strike Assad when such legislative authorization was not forthcoming–was to be commended, and welcomed, as consistent with the constitutional design.

There is no apparent justification for President Trump not to have asked Congress for such authorization here, and to have held off on the strikes until receiving such authorization.  Therefore, this might turn out to be the rare case in which the President simultaneously violates both the Constitution and the Charter.

* * * *

What follows is an excerpt of my very simplified 2013 account of the complex, longstanding constitutional debate about the President’s constitutional authority to use military force without congressional authorization, and its application to President Obama’s contemplated use of force against Syria in 2013:

In the past two generations, there have been three principal schools of thought on the question of the President’s power to initiate the use of force unilaterally, i.e., without congressional authorization:

a.  The traditional view, perhaps best articulated in Chapter One of John Hart Ely’s War and Responsibility, is that except in a small category of cases where the President does not have time to wait for Congress before acting to interdict an attack on the United States, the President must always obtain ex ante congressional authorization, for any use of military force abroad.  That view has numerous adherents, and a rich historical pedigree.  But whatever its merits, it has not carried the day for many decades in terms of U.S. practice.

b.  At the other extreme is the view articulated at pages 7-9 of the October 2003 OLC opinion on war in Iraq, signed by Jay Bybee (which was based upon earlier memos written by his Deputy, John Yoo).  The Bybee/Yoo position is that there are virtually no limits whatsoever:  The President can take the Nation into full-fledged, extended war without congressional approval, as President Truman did in Korea, as long as he does so in order to advance the “national security interests of the United States.”  With the possible exception of Korea itself, this theory has never reflected U.S. practice.  (Indeed, even before that OLC opinion was issued, President Bush sought and obtained congressional authorization for the war in Iraq.)  Notably, it was even rejected by William Rehnquist when he was head of OLC in 1970 (see the opinion beginning at page 321 here).

c.  Between these two categorical views is what I like to call the Clinton/Obama “third way”—a theory that has in effect governed, or at least described, U.S. practice for the past several decades.  It is best articulated in Walter Dellinger’s OLC opinions on Haiti and Bosnia, and in Caroline Krass’s 2011 OLC opinion on Libya.  The gist of this middle-ground view (this is my characterization of it) is that the President can act unilaterally if two conditions are met:  (i) the use of force must serve significant national interests that have historically supported such unilateral actions—of which self-defense and protection of U.S. nationals have been the most commonly invoked; and (ii) the operation cannot be anticipated to be “sufficiently extensive in ‘nature, scope, and duration’ to constitute a ‘war’ requiring prior specific congressional approval under the Declaration of War Clause,” a standard that generally will be satisfied “only by prolonged and substantial military engagements, typically involving exposure of U.S. military personnel to significant risk over a substantial period” (quoting from the Libya opinion).

Largely for reasons explained by my colleague and Dean, Bill Treanor, I am partial to this “third way,” at least in contrast to the two more categorical views described above.  (I do not subscribe to every detail of the Dellinger and Krass opinions—in particular, I’m wary of resort to the interest in “regional stability,” which has never been used as a stand-alone justification for unilateral executive action—but I concur in the broad outlines sketched out above.)  Regardless of whether Dean Treanor and I—and Presidents Clinton and Obama—are right or wrong about that, however, what’s important for present purposes is that U.S. practice after World War II (with the possible exception of Korea and Kosovo) reflects, and is consistent with, this “third way” view:  When a prolonged campaign has been anticipated, with great risk to U.S. blood and treasure, congressional authorization has been necessary—and has, in fact been secured (think Vietnam, both Gulf Wars, and the conflict with al Qaeda).  Otherwise, the President has considered himself free to act unilaterally, in support of important interests that have historically justified such unilateral action—subject, however, to any statutory limitations, including the time limits imposed by the War Powers Resolution.  See, e.g., Libya (twice, 1986 and 2011), Panama (1989), Somalia (1992), Haiti (twice, 1994 and 2004), and Bosnia (1995).

Assuming this “third way” view is correct—or, in any event, that it establishes the relevant historical baseline against which to measure the case of Syria— . . . all of the examples of unilateral presidential use of force since 1986 (with the possible exception of Kosovo, discussed below) have been in the service of significant national interests that have historically supported such unilateral actions—such as self-defense, protection of U.S. nationals, and/or support of U.N. peacekeeping or other Security Council-approved endeavors and mandates (e.g., Bosnia and Libya).

The [contemplated Obama] Syria operation, however, would have had no significant precedent in unilateral executive practice; it would not have been been supported by one of those historically sufficient national interests.  That’s not to say that that operation would not be in the service of a very important national interest.  For almost a century the U.S. has worked assiduously, with many other nations, to eliminate the scourge of chemical weapons.  If Syria’s use of such weapons were to remain unaddressed, that might seriously compromise the international community’s hard-won success in establishing the norm that such weapons are categorically forbidden, and should not even be contemplated as instruments of war.  As Max Fisher has written, “it’s about every war that comes after, about what kind of warfare the world is willing to allow, about preserving the small but crucial gains we’ve made over the last century in constraining warfare in its most terrible forms.”

Preventing that degradation of the strong international norm against use of chemical weapons is, indeed, an important national (and international) interest of the first order.  (To be clear:  I am not remotely qualified to opine on whether and to what extent the contemplated action would advance that interest—my point is only that the interest is undoubtedly an important one.)  And perhaps that should be enough to justify discrete, unilateral presidential action short of “war in the constitutional sense.”  But if so, it would nevertheless be an unprecedented basis for unilateral executive action, and it would open up a whole new category of uses of force that Presidents might order without congressional approval, even where such actions could have profound, longstanding consequences:  Most obviously, think, for example, of possible strikes on Iran in order to degrade its nuclear capabilities. . . .   At a minimum, it’s a profound, and heretofore unresolved, question, one that any President should be wary of raising.


* In 1989, OLC notably (and somewhat notoriously) concluded that because Article 2(4) of the Charter is non-self-executing, in the sense that it does not establish a rule for court adjudication, it is “not legally binding on the political branches,” and thus “as a matter of domestic law, the Executive has the power to authorize actions inconsistent with Article 2(4) of the U.N. Charter.”  13 Op. O.L.C. 163, 179.  In my view, this understanding of the effect of a “non-self-executing” treaty is importantly mistaken: It is simply a non sequitur to reason, as OLC did, that because Article 2(4) is “non-self-executing” in the sense that it does not provide a basis for judicial intervention, the President is therefore free as a matter of domestic law to ignore that provision and deliberately put the U.S. in breach of its treaty obligations.  That deeply counterintuitive position does not reflect the views either of the parties to the Charter (every nation in the world), or of the President and the Senate that approved it for the United States in 1945.  This is a much broader topic, for another day, however.  I am not aware of any indication that the Clinton Administration adopted this position with respect to Kosovo in 1999.  If the Trump Administration does so, I might have more to say about it then.

Image: The guided missile destroyer USS Barry (DDG 52) launches a Tomahawk cruise missile March 29, 2011, in the Mediterranean Sea while operating in support of Operation Odyssey Dawn – Dep’t of Defense