People may have missed it, but in comments yesterday Marty Lederman left the following remarks with regard to presidential war powers:
1. The War Powers Resolution does not prohibit any initiation of hostilities. Section 2, which Jim Henley quotes, is merely hortatory -- it expresses Congress's view of when the President can act unilaterally as a matter of constitutional authority. It does not itself impose any limitations. (And as Dellinger pointed out, *everyone* agrees that section 2 is inadequate as a descriptive matter, although there's a lot of dispute about how far the President's constitutional powers extend.)
2. The War Powers Resolution does require the President to get congressional approval if hostilities last beyond 90 days. The OLC Opinion that Matt links concluded (controversially) that appropriations statutes for Kosovo provided the requisite congressional approval for going beyond 90 days there. A similar question would arise if an Iranian conflict goes beyond 90 days; but we're not there yet, obviously.
3. The big question here is not the War Powers Resolution, but the Constitution. What sorts of hostilities can the President initiate unilaterally under the Constitution? Matt is right that the Clinton Administration took a very broad view -- see Haiti, Bosnia Bosnia and Kosovo, for starters; we basically concluded that congressional pre-approval is only required for a complete, or total, war (see footnote 5 of the Bosnia opinion, hinting that the Korean War might have been unlawful because Congress had not authorized it in advance).
The Bush Administration view is broader than that, if that's possible. There is no doubt Bush believes he has the authority to initiate all-out war with Iran, although of course the initial forays will be more limited than that (e.g., "surgical" strikes) -- which even the Clinton Administration would have viewed as constitutionally permissible.
So as a *practical* matter, the issue is determined -- the President believes he has the power, and he won't hesitate to exercise it.
Unless Congress actually passes a statute, probably over Bush's signature, that would *prohibit* military action against Iran. Bush might go ahead anyway, in the teeth of such a statute, because in this respect his views of executive authority go way beyond Clinton's. But that truly would be an unprecdented constitutional showdown.
And it, too, is hypothetical, because Congress won't enact such a statute.
Therefore, what's most interesting about this whole incident is Hillary Clinton taking a narrower view of presidential authority than Bill did as President -- that *any* use of force against Iran requires congressional approval! Frankly, I'm surprised she has expressed such a view. Be interesting to see how Edwards and Obama respond.
Clearly, as long as George W. Bush is president, I think presidential war powers, like presidential powers in all respects, should be as sharply limited as possible. On the actual merits of the issue, I'm not really sure how I think the congress-president balance in such matters should go. As a general matter, I tend to think parliamentary systems as seen in Britain or Canada are superior to our method of government. A system like that puts less formal restraint on the head of government in terms of his ability to act, but also makes it much easier to dump a head of government whose policies have failed and whose leadership is widely considered inept.