Let’s assume the probable: that like Saddam Hussein after 1991, Syria’s leader, Bashar al-Assad, convinced that U.S. President Barack Obama is channeling Neville Chamberlain, more-or-less conspicuously obstructs the handover of his chemical weapons to some form of international control and, coincidentally, continues butchering men, women and children by more conventional means.

And then let’s assume the less probable, that Obama discovers his inner Winston Churchill. Can he then introduce Assad to a little missile-delivered ‘shock-and-awe’ without violating international law?

What follows is going to make you empathize with Harry Truman who, according to apocrypha, once asked for a one-armed lawyer because ‘All the other ones say, “On the one hand … on the other.”’ Even I, a lawyer, empathize with Truman. Still, I can’t change the nature of law, well, more precisely, the nature of rules.
Behind the rule lies a premise

A rule is a generalized behavioral directive. Things such as ‘don’t deliberately shoot someone!’ or ‘wait until the light turns green before entering an intersection.’ Behind the rule lies a premise, namely, that society will be better off if everyone obeys the rule. In a well-ordered society the premise is usually right. But there are circumstances where following the rule will seem wrong. Suppose I am a kindergarten teacher with a Glock in my bag and I see a crazy-looking guy about to shoot one of my students. Or, to take my other rule, suppose it is two in the morning on a remote country road and I am rushing a stroke victim to the county hospital and there is not a car in sight as I approach an intersection with a red light. If you tried writing all the scenarios to which the rule applies into the rule itself, every law would be the size of the Old and New Testaments and still you would fail, because words are fixed while the circumstances to which they are directed are infinitely varied.

So while what is legal or illegal is often clear, otherwise society could not function, sometimes it isn’t. At least in an effective national legal system you have courts with compulsory jurisdiction, staffed for the most part by judges without any financial interest in the outcome of their cases who deliver a stream of judgements applying rules to particular situations. And situations tend to be patterned so most of the time you can figure out by analogy how the rule will apply to your situation. Yet still there will be configurations of facts which are a sufficient deviation from the norm to force honest lawyers to give their clients the ‘I’m not sure’ answer.

In the international system, there are no courts of compulsory jurisdiction staffed by more-or-less independent judges. Instead, the stream of decisions is constituted primarily by the applause, condemnations, and silences, the acts and omissions of the very governments the rules are supposed to direct.

If one were to ask John Bolton, President George W. Bush’s U.N. ambassador, his answer (I presume, having read his writings) would be: ‘You fool, you’ve begged the question since there is no international law: there are just political understandings which, when they don’t work for us we should ignore, because unlike our own real “laws”, their violation carries no moral stigma.’ But ask former Secretary-General Kofi Annan and he presumably will repeat what he said during the NATO air campaign against Serbia: ‘Only the Charter provides a universally legal basis for the use of force.’ With this statement, he reflected the views of most diplomats and political leaders because most countries lack the capacity – and many lack the interest – to project force beyond their frontiers. And when they use the word ‘law’, they mean to distinguish binding agreements from merely convenient ones.
Syria is a more exceptional case

Under its most natural reading, the U.N. Charter prohibits the use of force for any purpose other than ‘self-defense against armed attacks’. But the Charter’s ink was hardly dry before a number of governments, backed by friendly scholars, found ways of parsing Charter language to make room for other uses of force.

Their legal creativity and, more to the point, the variety and frequency of uses of force beyond self-defense against an armed attack led a committee appointed by a former U.N. Secretary-General – a committee of persons inclined to oppose the use of force without Security Council authorization – to conclude that the Charter restraints never got traction in the practice of states; that in effect the relevant provisions had been like a stillborn twin of the rest of the Charter.
However, they attributed this morbid prodigy to the Cold War and concluded from their consultations with diplomats and political leaders that now, at last, there was readiness to accept unprecedented restraint on military power because almost all countries rejected the idea of governance by some kind of unipower. Yet when in the wake of the Cold War NATO bombed Serbia to halt ethnic cleansing in Kosovo, the Russians could not marshal anything approaching a majority in the Security Council to denounce this humanitarian intervention.

I think Syria is a more exceptional case than Kosovo. Not only has Assad orchestrated mass murder, consciously converting unarmed demonstrations into a civil war of awful proportions that clearly threatens the peace and security of the entire region in a way Kosovo did not; his forces have also used a weapon that the overwhelming majority of states have agreed not even to produce and store, much less employ.

But arguably the most relevant assessment cannot be made by applying legal technique, by the parsing of texts and the deployment of precedents. For purposes of global order and American influence in this networked era, that assessment will be made by people in the shops and coffee houses, the factories and student unions and Tahrir Squares of the world, and they will do so more in terms of justice, morality and reasonableness than the idiom of law.

It’s a good cause but a tough sell, Mr. President. Hopefully as you invoke the poison gas taboo, few will recall that when Saddam Hussein employed that weapon against the youth of Iran, the United States helped him locate his targets. You are heir to a chequered history of moral concern. So are we all.