At West Point, the principle of morality taught that legislates this type of case is the Doctrine of Double-Effect. To grossly oversimplify, this principle states that those actions are acceptable that do not aim to harm an innocent person. By this light, the strike on Anwar al-Awlaki was the intention— which was justifiable in the Obama administration’s eyes as he had renounced his citizenship— while the secondary effect of the death of his son, verily unfortunate, was simply collateral damage in a strike necessary to the security of the United States. Under this principle due process doesn’t enter in to the equation.
I’m not saying whether or not I think this is a good principle on which to evaluate actions, but simply attempting to highlight the different doctrines that come into this argument. Libertarians are probably unlikely to find the DDE appealing, but most who deal in military affairs and national security find it compelling and perhaps even necessary.
Yeah, that argument might be relevant if the kid weren’t targeted in a completely separate attack TWO WEEKS after his father was assassinated.
This was not collateral damage.
This was not an accident.
This was not the price we had to pay for safety.
This was intentional assassination of a child.
Also, murdering people without due process is wrong no matter what citizenship they do or don’t have, because “It is indisputable, well-settled Constitutional law that the Constitution restricts the actions of the Government with respect to both American citizens and foreigners. It’s not even within the realm of mainstream legal debate to deny that.”
The constitutional amendments protecting trial rights say “person,” not “citizen,” with good reason, and it means that Abdulrahman al-Awlaki AND his father were guaranteed a fair trial. Obama ignored the Constitution to specifically assassinate a boy, period.

