The "Uniting for Peace" doctrine, invoked in November 1950 via its resolution 377A(V), allows the UN General Assembly to recommend collective action when the Security Council, because of lack of unanimity of the permanent members, fails to exercise its responsibility in a matter. In 2004 the International Court of Justice approved this doctrine when it confirmed that the prohibition of simultaneous action in Articles 11 and 12 of the UN Charter had been superseded by practice (I.C.J. Reports 2004, p. 136, at paragraphs 27-28).
Yet as far as I know there has been no attempt in the current Syrian controversy to invoke Uniting for Peace. Instead the US has maintained that it must in the face of differences with China and Russia act on its own, with whatever support from other nations it can garner. And the commentaries I've read don't allude to Uniting for Peace; they either support independent action by the US or oppose it; and those who oppose it (such as Pres. Putin in his recent letter to the New York Times) often cite the requirement for Security Council action, without any consideration or even mention of Uniting for Peace.
My question is: Why is Uniting for Peace not given any consideration in the current Syrian controversy?