To wind up my round of posts on the WPR, let's ask whether it made a difference. As was the case last time, I want to take several steps back from the standard debate. This debate proceeds in terms of multiple examples of presidential military action in which the WPR was either basically invoked (Reagan in Lebanon) or not (reflagging Kuwaiti tankers) or wasn't relevant because the action was quick (Grenada-Panama). While scholars have drawn different conclusions from different examples, no one argues the WPR was a success story. At the same time, this observation has to be taken with a grain of salt, given that few set forth realistic criteria for success.
The WPR's supporters saw it as a constraint on presidential action, although some leeway was given in terms of the 60 day clock. Given the evidence available, we have to ask whether the WPR was more of an effect rather than a cause. The history of the period seems pretty clear that all post-Nixon presidents were very well aware that the public wanted "no more Vietnams." Slightly more pejoratively, this was known as the "Vietnam Syndrome." At least within the period of the cold war, the public got what it wanted. There was never again a war that cost anything even remotely close to the 55,000 names that are inscribed on the wall on the Mall. There is a line of analysis that says this was inevitable. We could not have another draftee army being chewed up in a foreign locale once the all-volunteer military was adopted. But surely it was still possible to have a lengthy unproductive military involvement on a major scale even with the AVF. We learned this eventually in Iraq. Again, however, within the cold war nothing like Vietnam ever happened again. It's striking how many times a fear of Vietnam was raised in the 1980s in implausible circumstances like Grenada and worrying about advisers in El Salvador.
No more Vietnams was in fact officially adopted by at least part of the executive branch. It was codified in the Weinberger-Powell doctrine. This doctrine included the principle that any major military action must be supported by the public. Because this was also the basic purpose of the WPR, one would think that liberals might have hailed this doctrine as accepting the basic premise of the WPR and we might as well all go home friends. I haven't found any evidence of this. Perhaps Weinberger had too little credibility in Congress for anyone to pay serious attention to his criteria. But surely it had to dawn on some supporters of the WPR in the 1980s that the military and the civilians running the DOD were in earnest about not fighting any more wars without public support. That would entail at least some sort of congressional authorization, which would satisfy the WPR.
Even after the cold war, President GHW Bush likely only felt safe approving the Gulf War in the belief that it would be relatively brief. James Baker's memoirs record a suggestion made at one point in executive branch deliberations over whether to go to war -- invoke the WPR and just make sure the war lasted less than 90 days! That way, Congress would be left hanging with no objection even if Bush never asked for authorization. Baker says this was considered too clever and I agree. And despite Bush's clear resolve to initiate war without congressional authorization, it is true that in the end he did not bypass Congress. He expended a great deal of effort making sure he would win the vote to authorize the war, as you would expect from a political point of view.
Although I don't agree with much in the recent Posner-Vermuele book on executive power, I have to admit that the "no Vietnams" saga illustrates the primacy and relevance of political, as opposed to legal, constraints on the executive. Quite a lot of evidence supports the idea that presidents were restrained in the exercise of military power post-Nixon. But not primarily because of the WPR. Presidents did not ignore the WPR, as often implied in overly general journalistic accounts. But the reason Ford, Carter, Reagan and Bush avoided a major war was because of an enormous consensus that the country wanted no more. This consensus had positive and negative consequences for foreign policy. It seems difficult to deny, however, that this political consensus was the motive force behind many presidential decisions of the period, not the WPR. Perhaps we should pay less attention to whether presidents complied with the details of the WPR, and more to the political context in which presidential decisions were made.