Some of you guys have a heck of a lot more trust in the government than I do.
We've used extrajudicial killings of citizens who have taken up arms against the state since before the US formally existed (see: Tory's, Whiskey Rebellion, Civil War, WWI, WWII, etc). I'm still trying to figure out how the Civil War would have turned out if the Union Army hadn't been able to, you know, carry out extrajudicial killings of rebel soldiers on the field of battle... I'm guessing Gettysburg might have turned out somewhat differently?