Hillary Clinton's vote against the FISA reform bill this week seems to have taken quite a few people by surprise, and it's engendered a lot of speculation as to why she voted the way she did, even as Barack Obama supported the bill. She didn't have any strong political incentive to vote yes, and while Obama is generally regarded as having some civil-libertarian leanings, Clinton has been more widely described (by TNR's Michael Crowley, among others) as a genuine executive-power enthusiast.
Suppose that, in addition to the merits of the legislation and the obvious political considerations involved, one reason that Obama supported the bill is that he believes he'll probably be the next president, and he wants to give himself more authority. Though there's clearly no way to know for sure, it's just as possible that the reverse is true--that Clinton's support for a strong executive was founded in some measure on the (not unreasonable) belief that she was likely to be a future occupant of the Oval Office, and that now that she knows she'll be in Congress for the foreseeable future, she's suddenly become an ardent defender of legislative power. (Consider her statement explaining her vote: "Congress must vigorously check and balance the president even in the face of dangerous enemies and at a time of war.")
If this is true--if Clinton's views of the relative benefits of executive and legislative power are devoid of principle and are merely a function of whichever office she has her eye on at the moment--I say: You go, Hillary! We need more members of Congress who think that way. In an ideal world, everyone in Washington would agree on a reasonable, textbook allocation of powers between the branches of government. But that's never going to come to pass. In the real world, separation of powers depends on each branch jealously guarding its own turf. In recent years the executive branch has certainly done this (indeed, it's gone well beyond what past administrations have deemed necessary or defensible). The Supreme Court, likewise, has been a strong force for judicial power.
Congress, on the other hand--more so before the Democratic takeover in 2006, but to some degree even afterwards--has been meek and pliable, out of partisan loyalty to the president (in the case of Republicans) and for fear of stirring up controversy (on both sides of the aisle). When James Baker and Warren Christopher this week released their plan calling for an institutionalization of Congress's role in the realm of war powers, Tim Noah in Slate rightly pointed out that Congress has all the authority it needs; the problem is that most members of Congress don't want any real say in the process, since they're so narrowly focused on winning re-election and would like to avoid being held accountable for tough, controversial decisions. Ben Wittes makes a similar point in his new book: Congress has had no interest in taking the lead in crafting a detainee policy for which it could later be blamed if things go awry.
It's beyond me why members of Congress would go through all the hassle and trauma of getting elected in order to have a nice title and a fancy office while being ignored by the other branches of government on the most salient issues of the day. But if Hillary Clinton is looking for a worthy and neglected cause to champion during her post-2008 Senate career, she could do much worse than cajoling her fellow Capitol Hill denizens to start throwing some elbows and pushing back a little bit (even if, deep down, she'd rather be at the other end of Pennsylvania Avenue, running roughshod over them).