that pesky Constitution that guaranteed him a jury trial. That legislation when used to deprive Americans of their Constitutional rights is invalid.
Have you read the text of the 5th Amendment recently? Please allow me to remind you of it...
"No person shall be held to answer for a capital, or otherwise infamous crime, unless on a presentment or indictment of a Grand Jury, except in cases arising in the land or naval forces, or in the Militia, when in actual service in time of War or public danger; nor shall any person be subject for the same offence to be twice put in jeopardy of life or limb; nor shall be compelled in any criminal case to be a witness against himself, nor be deprived of life, liberty, or property, without due process of law; nor shall private property be taken for public use, without just compensation."
Not that the word "citizen" or "American" does not appear in the text. It is "person". The 5th Amendment is not citizenship specific (neither are the 6th, 7th, or 8th, which also deal with jurisprudence). So, please stop beating that drum.
Apples and oranges. Americans are different than the enemies we usually face.
The Constitution protects Americans from that legislation.
Nope, and nope. The text does not support that interpretation.
So, now we have an issue. When the 5th through 8th amendments apply, they apply to everyone, regardless of citizenship. We are now dangerously close to saying that the US cannot prosecute a war, because it cannot deprive anyone of life without due process of law, and you define that as trial by jury. This is clearly a balderdash interpretation, as the document was written after the Revolutionary War - the Founding Fathers clearly believed that war was okay. The 5th includes, "...in time of War or public danger". They recognized there were exceptional circumstances where normal jurisprudence did not apply - war *and* public danger.
Then, we have a sticky bit. The Constitution does give Congress the power to declare war. But, it *DOES NOT DEFINE WAR*, nor even how Congress should go about declaring it. The document also declares the President to be Commander-in-Chief of the armed forces - presumably with attendant rights to give particular orders.
We might take the AUMF to be a declaration of war - nowhere are we told that the declaration must include the word "war". We can certainly take it as a declaration of a time of public danger, as it references stopping future attacks. It seems pretty clear that Congress intended this to be considered a time when normal jurisprudence did not apply to members of Al Qaeda.
If Congress wanted to, at any time they could have rescinded the AUMF, and remove the President's power to order the military to attack Al Qaeda. They didn't.
We may find it unseemly, and undesirable for our military forces to be used in such a manner. That doesn't mean they were technically illegal. We may, in retrospect, have preferred such action not be legal - but hindsight is 20/20. We should not hold people accountable for the unintended consequences we were not wise enough to consider, retroactively. Next time, elect thoughtful Congresspeople who put limits on authorizations of use of military force, and move on.