Why? Because he doesn't hold that power. That is for a jury wether it be of civilians or a military tribunal.
He indeed was captured inside the borders of this nation and the courts have now applied our constitution to those folks that are, wether they are citizens or not. Hence padilla being transferred to civilian custody. See the pattern? Does it scare you? I hope so, it should.
What excuse? How about the ACLU and leftist judges and lawyers that agree with them. You know, the crew that has made it almost impossible to direct enforcment of laws by creating excuses that somehow release personal responsibility.
The President absolutely has that power. The US Supreme Court in ex parte Quirin approved the use of military tribunals, but also ruled that they were not necessary.
The tribunal proceedings in 1942 were not a trial of any sort. They were not conducted according to the rules for courts martial.
The sole function of the tribunal was to affirm that the individuals to be executed were in fact Germans out of uniform and behind our lines.
In the ZM case, such fact finding was unnecessary.
George W. Bush could absolutely have ordered ZM's execution at any time after 9:03 AM on 9/11/01, solely on his own authority.
That he did not do so is shameful.