National Review has posted a symposium on the constitutionality of the Libya intervention. The symposium includes a large number of legal scholars and commentators, mostly conservative ones, as one would expect from a conservative publication. Interestingly, most of the participants reject the view (advanced by John Yoo and some others in the George W. Bush administration) that the president has unilateral authority to commit US forces to battle at any time, regardless of the scale of the conflict envisioned. My own contribution to the symposium is here. It largely tracks the position I outlined in greater detail in several VC posts on this issue (see here, here, and here).
My bottom-line view is that, while the president can undertake small-scale military actions on his own, engagements large enough to amount to a “war” require congressional authorization, unless the president is responding to an actual or imminent attack. The fact that we cannot draw an absolutely precise line between the two categories doesn’t mean that the distinction between them is meaningless, any more than our inability to precisely specify the exact minimum height at which a person can be considered “tall” proves that there is no meaningful difference in height between a seven foot tall man and one who is only five feet tall.