Quote from DAS Trader:
Your hyperbole aside, he was a US citizen and the Constitution has a process for dealing with US citizens who commit treason (i.e. enemy combatant would be a form of treason...for clarification see the excerpt from the Constitution I posted previously). The President swore an oath to defend the Constitution and he ignored that oath when he assassinated Awlaki. Nowhere in the Constitution does it say "well, if he's an enemy combatant just drop a bomb on him and it's all good". Being labeled an enemy combatant does not negate his Constitutional rights.
Oh, and your solution to the problem, which seems to be kill em all and be done with it, has one flaw. What if someone gets labeled an enemy combatant who was not, in fact, an enemy combatant? Should we just kill them anyway?
What if one day you post something on line and someone with authority takes it the wrong way and labels you an enemy combatant...would you support the application of your solution then?