I'm a longtime advocate of the position that, cases of clear self-defense aside, Congress should issue a declaration of war before the president commits combat troops overseas. At the same time, I recognize that this virtually never happens anymore. At best we get vaguely worded "authorizations of force," at worst we get nothing at all. Every president since Roosevelt, and most of them before him, have operated this way. So I'm not especially put out that President Obama failed to get congressional approval before committing the United States to support the no-fly zone over Libya. He's just acting the way every president in recent memory has acted. Matt Yglesias offers up this explanation for our current state of affairs:
The main reason congress tends, in practice, not to use this authority is that congress rarely wants to. Congressional Democrats didn’t block the “surge” in Iraq, congressional Republicans didn’t block the air war in Kosovo, etc. And for congress, it’s quite convenient to be able to duck these issues. Handling Libya this way means that those members of congress who want to go on cable and complain about the president’s conduct are free to do so, but those who don’t want to talk about Libya can say nothing or stay vague. Nobody’s forced to take a vote that may look bad in retrospect, and nobody in congress needs to take responsibility for the success or failure of the mission. If things work out well in Libya, John McCain will say he presciently urged the White House to act. If things work out poorly in Libya, McCain will say he consistently criticized the White House’s fecklessness. Nobody needs to face a binary “I endorse what Obama’s doing / I oppose what Obama’s doing” choice.
I think there's something to this, but it also strikes me as incomplete. After all, on domestic policy, the same dynamic applies: why not just let the president do what he wants so that you remain free to criticize him without ever taking a firm stand? But that's not what Congress does.
Rather, there are certain specific areas where Congress has deliberately given up its authority. Warmaking is one. Monetary policy is another. Detailed federal rulemaking is a third. Each has a different justification. In the case of war, the theory is that an active executive needs to act quickly, free of congressional dithering and endless committee hearings. In the case of monetary policy, the theory is that politics will inevitably get in the way of decent policy, so Congress should voluntarily restrain itself. In the case of rulemaking, the theory is that there are simply too many rules and it's impossible in practice for Congress to consider them all.
Each of these theories has problems. With very rare exceptions, there's enough time for Congress to consider a declaration of war. They've shown they can act within a day or two if a situation is especially urgent. In the case of monetary policy, Congress could easily provide more specific direction to the Fed even if they don't intervene in day-to-day open market operations. And Congress, if it wished, could insist that federal rules be bundled into packages and passed only after an up-or-down vote in the House and Senate, no amendments allowed.1
Proposals to reform this stuff come up now and again, but it never happens. The War Powers Act was the last time Congress tried to assert some authority in the area of warmaking, and its practical effect was negligible. There's occasionally talk of making the Fed more accountable, but it never goes anywhere. And there's frequently talk of changing the rulemaking process, but it also goes nowhere.
So why these three areas, plus a few others, but nothing else? Is it just inertia and tradition? Or is there something special about them? My vote is mostly for inertia and tradition. There's no really persuasive reason why Congress should have decided to abdicate its authority in these areas but not others, but they have. And once power is abdicated, it's rarely regained.
1There are legal obstacles to all of these things. However, as near as I can tell, they could mostly be overcome if Congress truly asserted itself.