Law in War Isn’t as Irrelevant as People Fear

But it still should matter more than it does.

Donald Trump in front of an American flag.
Tom Brenner / Reuters

President Donald Trump’s claim last summer that the Constitution gives him “the right to do whatever I want as president” was promptly—and rightly—condemned as constitutional fantasy by prominent liberals and conservatives alike. That “ours is a government of limited powers” is as foundational a constitutional principle as they come.

Yet watching the consequences of the president’s decision making unfold, many were left wondering whether law could change the course of events. Indeed, conventional constitutional wisdom has long held that law matters little in executive-branch decisions about the use of military force. In this telling, the Constitution is notoriously indeterminate about how exactly power over force is to be divided, and in practice, no other branch of the government stands between the president and military action anyway. Courts have avoided ruling on the constitutionality of even the most controversial uses of force—where the courts’ input would be the most valuable. Congress, too, has largely ceded its authority in this realm, preferring to let the president take the political hits for any deployment abroad gone wrong. And presidents time and again have used force abroad when they wanted to, with or without congressional approval.

But, as conventional accounts tend to do, this one overlooks a lot. Take Congress, for a start. Recent empirical scholarship has demonstrated convincingly that congressional support (or its absence) has been enormously consequential in shaping presidential willingness to continue to use force abroad. Likewise, the much maligned and regularly misunderstood War Powers Resolution—the 1973 law passed by Congress during the Vietnam era in an effort to reassert congressional supremacy on matters of war—succeeded in solidifying a requirement that the president notify Congress of the introduction of troops into hostilities abroad within 48 hours of any such action. And the reporting requirement is not meaningless. Though the Trump administration’s justifications for the attack on Iranian General Qassem Soleimani have been equivocal, officials had to provide Congress with a report within 48 hours of the strike about what had happened and why. And they did, albeit it in classified form. With debate already scheduled to begin in the coming days over legislation to restrict the president’s ability to take further action against Iran, the administration will feel pressure to keep that report classified. Either way, the report sets a key factual baseline for the discussion to come.

Indeed, the common habit of executive-branch compliance with this particular rule—yes, even the law-averse Trump administration has submitted War Powers Resolution reports to Congress repeatedly since taking office—points to another reason law still matters in executive-branch decision making surrounding the use of force: executive-branch officials have significant incentives to seek and follow clear legal guidance when it is available.

As part of a forthcoming study on the role of law and lawyers in executive-branch decision making, I have surveyed dozens of senior national-security policy officials who served in the George W. Bush and Barack Obama administrations, collecting their views on whether and why law might matter in shaping government decisions about the use of force. The most senior respondent served as a Cabinet secretary; the most junior served as a senior director on the National Security Council staff.

While the officials had widely divergent politics and views on many topics, there was absolute unanimity on the necessity of congressional notification before or (in the interest of protecting clandestine missions) immediately after a strike. Many officials had the sense that some law required as much, even if they could not name the law. All recognized that congressional notification served important interests—from political protection for the president, to personal protection for officials involved, to more abstract concerns such as the institutional prerogatives of Congress and the overarching sensibility that, as one official put it, “people don’t like the idea of a king.” And, especially when the legal question was about something more complicated than “notify Congress,” these officials said they regularly, repeatedly sought legal advice from government attorneys.

Which brings us to the constitutionality of what the current president has just done. For all the controversy surrounding the scope of presidential war powers, there is no dispute among constitutional scholars that presidents have at least some power under Article II to act in defense of American embassies and of Americans abroad without waiting for Congress to authorize the use of force first. Presidents long predating Trump have done so repeatedly. The dispute now is whether this constitutional power is more limited when a putatively defensive action risks triggering a much broader conflict, including full-scale war.

Inside the executive branch, lawyers in the Justice Department Office of Legal Counsel (OLC) in Democratic and Republican administrations alike have long taken the position that the president has the power to use military force without prior congressional authorization if the anticipated “nature, scope, and duration” of the operation would make it something less than “war” within the meaning of the constitutional clause giving Congress the power to declare it. “War” in this constitutional sense, the OLC suggests, lasts over time, involves multiple attacks, and, perhaps above all, poses risks to American lives. A singular drone strike is surely less than that, the president’s lawyers unsurprisingly advised.

But, the argument goes, any reasonable president would have to understand that this attack on Soleimani—as with any singular military strike against, for example, North Korea—carries enormous risks of escalation into a conflict of much greater scope and duration. In the wake of the attack, leaders around the world issued calls for calm in the hope of avoiding just such an escalation; the State Department ordered Americans to leave Iraq immediately, and the Defense Department has already announced that it is deploying additional troops to the area.

That should change the constitutional calculus. But as it stands, nothing in the OLC’s prevailing guidance—or in the Constitution more broadly—requires the president’s judgment to be reasonable. And everything in the OLC’s guidance—as it has evolved, unchecked by Congress or the courts, since 1973—leaves judgment of anticipated consequences up to the president alone. This is not to suggest that the OLC’s guidance is the final word on the meaning of the Constitution. (As a federal judge recently wrote in rejecting the administration’s claim that its officials are absolutely immune from testifying before Congress, the longevity of OLC opinion “does not transform an unsupported opinion into law.”) This is to suggest that the president’s lawyers’ failure to constrain his action here was entirely predictable; they told him essentially the same thing that any number of past OLC opinions have said: Singular strikes, less than all-out war, that serve the national interest as the president sees it need no prior congressional approval. This is not a failure of constitutional law as much as it is, at least in part, a failure of constitutional lawyers.

Government lawyers have an extraordinary capacity to influence policy outcomes. Decision makers understand that establishing the mantle of legality is important to securing Americans’ support for ongoing hostilities, reinforcing the nation’s confidence that America is in the right, and convincing America’s allies to support whatever lies ahead. And it is understandably tempting to let legal guidance dominate discussion: figuring out what the law says about going to war is almost always easier than figuring out whether going to war is actually a good idea. That makes lawyers’ duty especially weighty, as it includes telling the president that the Constitution doesn't leave warmaking to him alone.