Let's consider the case of Benedict Arnold.
After his plot failed, Arnold fled to British lines, was given the rank of Brigadier General and then led a British attack upon Virginia that captured Richmond.
Think of the ridiculous situation that "citizens can only be captured for trial" would result in:
Benedict Arnold is in camp. A local Virginia sniper knows a way to infiltrate close enough to the enemy camp to take a shot and kill Arnold. However, the sniper is told that he is not allowed to shoot at Arnold since Arnold cannot not be legally killed. However, the sniper can try to capture Arnold from within the enemy camp and bring him back for trial.
Arnold then stays in command of an enemy army that is waging war against Virginia.
Enemy combatants in command and control are legitimate targets of opportunity regardless of citizenship, past or present.
Sounds good, sounds reasonable.
Why did the 0bummer administration play games finding a way to Constitutionally justify killing him?
Benedict Arnold was never a U.S. citizen. The raid on Richmond took place in the winter of 1780-81, which was seven years before the U.S. constitution was ratified. He was a British subject and later a resident of Canada until the day he died.
I've got no love lost for this al-Awlaki guy, but if he was a U.S. citizen (I'm still not sure he was, in light of the fact that he attended college here in the U.S. on a student visa) then the manner of his demise should be disturbing to any self-proclaimed conservative on this site. I have yet to see anything in any media outlet that indicates exactly what rendered him a legitimate military target in a country that is not involved in a military campaign against the U.S.
Even aside from the lack of any due process in this case, what exactly were the charges against this guy?
You may be responding to the wrong person. I agree with you.
Al Awaki was a traitor. He is a legitimate a target.
He is treated as an enemy commander and can be killed on the battlefield.
Were he to have been captured, then yes, he unlike other Al Queda members would have had to be tried as a criminal and traitor in an Article III US Court.
On the battlefield (which in his case is any where he goes) he is an enemy and a target.