For MEB, forever.
It was bound to be the case that drone strikes would run a certain course, especially because of course Republicans are understandably bitter about Democrats bashing Bush for doing what he thought was required to protect the country, which obviously Obama came to realize was done for a reason to a point.
That is unsurprising because foreign policy is much more the realm of hard necessity than domestic policy, as to people having to do what they have to do.
(As to what was on Fox and Rush, Bill Ayers and all the active participants in Weathermen bombings should have been executed for treason, terrorism, and sedition. Why he is a hero to so many is beyond me. The key is taking up arms and/or providing those doing so with aid and comfort, treason, the only crime defined in the Constitution explicitly.)
As to killing foreigners, at whatever level of use of force, that's a policy question, and always has been and always will be, so long as all States, the Russia and China so much beloved of the Bolsheviks on this site, reserve the right to self-defense under Article 51 of the UN Charter.
There may be practical reasons not to do so, like Pakistani objections, although one can fairly wonder if they protest too much, in the sense of drone strikes in fact decimating the terrorists like Bin Laden that a nuclear armed state harbors, in order to harrass India, but lawful per se is very much a question of policy, like all international law.
As to the domestic legalities, as to killing foreigners, under our Constitutional order, the Senate is clearly intended to oversee the President in the field of foreign policy, as is the House per appropriations for Defense and Intelligence.
Should they actually wish to do so more actively, the legislators can merely ask for that oversight power, even sign off on the strikes, even put their names on the death warrant, although operationally speaking, that would probably have costs in terms of targets missed because of time, if potentially have some benefits keeping from getting out of hand with drone strikes in a way that harms American interests.
Just remember that people rightly complained about LBJ calling off airstrikes, so careful what you desire.
One wonders how much the Legislators really wish to dirty their hands.
As to the rare question of drone strikes on American citizens, in order to maintain cohesion in a demanding struggle that likely will never completely end, so we don't scare people like the Bolsheviks on this site, although ... or say at least as important survivalist types on the Right worried almost surely incorrectly to date as to a drone strike on their bunker in the desert, having more legal formalisms is probably now appropriate as to American citizens.
First, one wouldn't want the government to get too comfortable with the idea of killing American citizens, as if Al Alwaki was a righteous kill, his son... but then if you hang out with some people... what do you expect?
Secondly, and more importantly probably, the Bolshevik types who often populate this site seize any opportunity possible to harm the United States, because people like them have always been mortal enemies of this country, and always will be, discrediting them to the maximum extent possible is important, in terms of preventing their Pol Pot types from killing everyone here.
That is the history of people like that, everywhere they have ever been, and always will be. Them you can't use drone strikes on, alas, since they stay here, and usually stay just within the law, as to not advocating violence, although they never met a war they don't want us to lose, ever.
Therefore, in order to take away credibility from enemies of the United States, one needs to deny them things to complain about, one of which in the case, rare, of American citizens, would be to pass legislation using the FISA Court to keep a check on such strikes with American citizens.
Foreigners, that is fine if the Congress wishes to oversee, but hopefully as they do that, they will remember LBJ and his airstrikes.
As to the rare case of killing American citizens, the Foreign Intelligence and Surveillance Act Court exists for national security cases, because the Bolsheviks in the Soviet Union liked to infiltrate the United States, in order to destroy it.
That led to a different set of rules with them, or, we could have just surrendered to the Soviets then, or the jihadists now, but, FISA was a safeguard as to still being a country of laws, and an important one.
That is especially the case so as to not alienate Muslims here, the vast majority of whom are not a national security issue, and so not alienating them is important to achieve the policy objective of preventing terrorism by not overdoing things. Note, enemies of the United States wish to stir up as much Muslim hatred as possible, and so discrediting them is important.
All you have to do is have an amendment to the original use of force resolution for the Global War on Terror to have the FISA Court required to issue a warrant, or not, for, in effect, the killing of American citizens overseas. There can be no legal justification to attack American citizens on its own territory, because one can always by definition arrest on American territory, not the always the case overseas, also by definition.
All you have to do is establish language that if the Court cannot find a probable cause for a warrant for arrest for an American citizen on an aid and comfort charge of treason, sedition, which under Federal law would carry a death sentence, then no warrant can issue, even in the FISA Court, and so therefore no drone strike can follow on American citizens, since the operational decision to kill rather than capture in the execution of an arrest in terms of physical risks is not in its nature in the purview of any Court, especially outside the country.
It is a rare case, but one because of its serious consequences to the Constitutional order, ought to be taken seriously, in which the FISA Court would be reasonable as protection, if its hardly the case that the government is running around killing American citizens left and right either.
As to foreigners and drone strikes, the Congress is well-within its powers to monitor and manage the use of force, recognizing however that it is also mainly an Executive prerogative in its nature at the level of individual operations, as opposed to general character, including things like insisting on thinking through, "Are the drone strikes doing more harm than good in terms of alienating people overseas, or, is the shouting actually proof that they work, and then if that is the case, why listen to American enemies?"