Wow lawyers, lawyers every and not a chance to think. Here are the facts:
1. War has been declared against the US. [At first the US ignored this as rantings of fanatics and paid a big price.] While Congress retains the right to declare war on others, this is not the leftist dream world where it takes two to fight.
2. In this war the US naturally seeks to take out the command and control of the enemy.
3. So an enemy combatant was killed. He happened to be a US citizen, technically only, but he certainly was an enemy combatant.
4. Enemy combatants are not killed because of some crime they have committed. You kill them because they are on the other side and are trying to kill you. You do not need grand jury indictment for each soldier you kill on the battlefield again because they have not committed a crime, they are doing their “duty” but are on the other side. [Similarly you hold captured enemy combatants UNTIL the hostilities are over, they are not sentenced as they are not being punished.]
He wasn't when he was killed.