For those interested in arguments about international law and possible military intervention in Syria, I highly recommend great essays by two authors from the United Kingdom (as readers may recall, the UK government recently released a position paper justifying possible military action under a humanitarian intervention theory similar to the one articulated by the UK in Kosovo; these essays address that official position in offering the authors' own takes).
Sir Daniel Bethlehem (formerly the legal adviser to the British Foreign Office and currently a visiting faculty colleague of mine at Columbia) has a piece in EJIL Talk titled Stepping Back a Moment – The Legal Basis in Favour of a Principle of Humanitarian Intervention. Especially interesting is his argument about methodology for determining legality of force: "Legality ... often falls ultimately to be assessed by reference to a circumstantial appreciation of a range of factors rather than resting simply on some apparently trumping proposition of law. In the case of the law on humanitarian intervention, an analysis that simply relies on the prohibition of the threat or use of force in Article 2(4) of the UN Charter, and its related principles of non-intervention and sovereignty, is overly simplistic." Bethlehem goes on to discuss the various factors or threads that might be pulled together to construct a legal argument for intervention in this case.
Guglielmo Verdirame, Professor of International Law at Kings College London, previously posted this essay on EJIL Talk, titled The Law and Strategy of Humanitarian Intervention. Verdirame begins by stating his view that "there is a doctrine of humanitarian intervention under international law today, although I accept that this doctrine is controversial." The focus of his essay is on the strategy of humanitarian intervention, and especially the deterrence rationales that underlie the proposed intervention in Syria. For Verdirame, the strategic questions (are military strikes likely to succeed in preventing/deterring additional chemical attacks?) and the legal questions (is military intervention justified?) are linked: "The absence of a non-forcible alternative cannot alone justify the use of force, in either a legal or a strategic sense. The use of force must, on its own terms, offer at least a credible prospect of providing substantial humanitarian relief."
Both are very well worth reading.