For MEB, forever.
The most fundamental thing a government does is protect the life of its citizens, as to why it's not unreasonable to give pause when the government kills one it's citizens, wherever they may be, if the circumstances matter too.
Charles Krauthammer was right that the people storming beaches at Normandy didn't say"Any American citizens here go to the right please."
Note, there did exist Americans who were pro-Hitler.
Of course Krauthammer, one of the best voices in American opinion as to think carefully about over the years, not perfect, but very smart, often wise, also qualified that statement by saying that the war on terror is a new type of war, in that since as CIA nominee Brennan pointed out, terrorism is a tactic primarlily, as to serving variegated political ends historically speaking, part of the conceptual difficulty with the GWOT, the Global War on Terror.
It is a conceptual difficulty, because the GWOT in fact has many enemies only loosely associated, in the sense that al Qaeda is as much a spirit now as a group, popping up like a whack a mole game, in which not only are local conditions often at least as important as the global jihad against American power, but management therefore of local political issues often is actually probably more important in preventing terrorism, and in exerting U.S. influence, the latter invariably part of any State's foreign policy, like it or not.
For all the neo-communists who protest such things by reflex action, all they do mainly is like Stalinists of the past support the foreign policy of the Russian Federation and the People's Republic of China, if they do so in modern conditions mainly of naivete, and also still serve a very important function as to corrective argument about U.S. policy.
Debate is always important if we are to governed by laws, not drones, the most important contribution of Justices Brandeis and Holmes, if both saw some limits to free speech as to advocating violence too.
That utility of corrective debate is particularly important in the case of the GWOT, in which what the enemy or problem is remains so ambiguous in character, in which many other agendas could be supported under the GWOT banner that might be bad ideas as practical matters.
Having said that, it remains the case that the question of using drones to kill foreigners is very different than killing American citizens, if of course it's never trivial to kill anyone.
That is because States always claim the right to self-defense under Article 51 of the UN Charter, and because in the field of foreign policy, the Executive Branch has to manage things, practically speaking it being the duty of the Congress to oversee that at a high level, and not micromanage, just as the Commander in Chief shouldn't call in most airstrikes, like LBJ in Vietnam.
Killing American citizens on the other hand touches on the fundamental nature of our government, as a government of laws, not drones, if in the hard cases to date, one would want to be careful about the laws to make going forward.
Clearly one could use the FISA Court to make sure that any American citizen targeted by a drone would have been indictable as to probable cause, the execution of the warrant not being feasible allowed as to presumption if rebuttable like say Paris, common-sense being a fair assumption, and which therefore under a Use of Force resolution making force lawful, therefore allowing for other measures as to drone strike versus capture.
Clear warning of facing an American legal process could be required as part of that process, if that also might have effects one didn't want on balance too.
Obviously no one can lawfully claim that an American citizen on American territory could be lawfully killed in a drone strike, because when on American territory, there is no escape from the ability of lawful agents of the U.S. government to execute an arrest warrant. One can merely outwait the person in a bunker, like in Alabama, unless they have a hostage, in which other considerations as to risk to the hostage are lawfully allowed to govern.
If that isn't the case, observation of a felony in progress, then there's no lawful basis for executing a warrant using force, the Randy Weaver and Branch Davidian cases correctly perceived at the bounds of the law, although one cannot hide from arrest warrants that are lawful forever either. Common sense, and political feedback, in both cases got it about right, that people maybe were a little more cautious, if in such rare situations, people also got the point that there weren't good answers either.
As to why an Amerian citizen being on foreign territory is radically different, one cannot count on the cooperation of local law enforcement, if only because in for example the Tribal Areas of Pakistan, there is no such thing we understand as law enforcement.
There are pluses and minuses of allowing lawful killing of American citizens in that context.
To make such a thing lawful, instead of allowing the political process here to decide if it is good policy by feedback effects, might in the long run be something we regretted as to the precedent established, even the FISA Court idea having that risk as to a Star Chamber process that someday could be used to harass dissidents from American foreign policies.
That is the real complaint of the Left, although as to Al Qaeda in the cases at hand, that is also a hard case, as to why making no law might actually be better, instead of the feedback effect, like maybe someday the killing of Anwar al Awlaki's son.
As to the drone strike on Anwar al Awlaki, that the the author celebrated, as he had clear ties to the 9/11 hijackers among other things, and could have been indicted later in Yemen on a treason charge, as to aid and comfort for enemies of the United States calling for the death of American soldiers in front of the Internet, as to more than two witnesses to a specific act required under the only crime defined specifically under the Constitution.
Treason is the only crime defined in the Consitution, for the good reason that the Star Chamber courts of Henry VII, after offing Richard III, were in fact instruments of Tudor tyranny; judge, jury, and executioner.
As to the problematic case, pointed out by a radical Leftists in the main, note the really important thing being free speech per Brandeis and Holmes on this topic, Al Awlaki's son was not so clear in character as to what has been stated publicly, if one can see why that might have had to be done as to him seeking revenge inevitably.
But then that proves there is freedom that people can bring that up, and not find a drone lurking outside their window too.
So as to legalizing such things, it could be done narrowly with the FISA Court being a very logical place, by definition requiring fair warning, although one would also want to think carefully about the creation of a Star Chamber as lawful, instead of just allowing the politcal process to feedback what is popular or not.
Some day there may be a war that is a really bad idea, in which people have fled the country because it was unpopular, and could not as a practical matter survive here, since one cannot live in the United States if one is unpopular enough, alas, the prediction by the way of Alexis DeTocqueville of a popularity-contest democracy having that effect.
But then we often regret such things later, in which it is totally reasonable to have concerns about the non-judicially authorized killing of American citizens, and still be wary of having a hard case drive the evolution of the law, instead of free speech, per Brandeis and Holmes.
Treason isn't protected free speech, and Al Alwaki could have been indicted even under Brandenburg v Ohio as such, and as to advocacy of violence with concrete aims, as to the legal question of was it outlandish in character, as opposed note to whether drone strikes being a good idea in general.
And to date, in defense of the Obama Administration, it is three cases as has been described, two of which were very, very clearly indictable on a treason charge, and very clearly as well not capturable without the risk of a major foreign policy incident.
So be wary of hard cases making bad law, even as the mechanism of the FISA Court under an authorization of a use of force resolution would work, if it could become a Start Chamber, and to date, it would mainly protect the users of force in effect, instead of just having confidence that if they judge correctly, they won't be judged negatively in the court of opinion, which in our society still remains among the most powerful courts of law, in the end.