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.
Behind the rule lies a premise
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.