Also, as has already been said in other posts, the Al-Awlaki family begged the US Government for over a year to charge him with a crime, ANY CRIME, so that he could turn himself in and have his day in court. The US Government refused to ever charge him with a crime specifically so they could deny him his rights.
You guys need to stop pretending this was some American killed on a battlefield while shooting at US soldiers. All it does is make you look dishonest, so what is the point?
Now, are you ever going to answer why the US Government never bothered to charge him with a crime?
Congress did, in fact, declare war. It is well established in law that the Cobstitutional power to declare war doesn't require using any particular words, and that it may be conditional on either external events or executive determinations. The AUMF is, Constitutionally, a conditional declaration of war.
It's not, but that actually isn't relevant and doesn't matter in the Al-Awlaki case anyway.
The text of the AUMF specifically references those who participated in or planned 9/11, which means it's not relevant to Al-Awlaki. Also, Al-Awlaki's family offered to have him turn himself in the second he was charged with a crime but the US Government refused to charge him since that would immediately guarantee him Due Process which they specifically sought to avoid.
The Constitution doesn't refer to battlefields at all. It does give Congress the power to declare war, which it exercised via the AUMF. There are numerous cases establishing that, in war, US citizens who are combatants of the enemy are not entitled to special treatment.