I can't reply to your last comment since it's nested so deep: "Help me understand how you read "courts may not inquire into the President’s motives", then. That's a ruling, by the Supreme Court, that they can not do so in this specific case."
There's scopes to the application of the ruling. An extrajudicial killing of a political opponent certainly falls outside of scope.
Help me understand how you read "courts may not inquire into the President’s motives", then. That's a ruling, by the Supreme Court, that they can not do so in this specific case.
The decision literally states "In dividing official from unofficial conduct, courts may not inquire into the President’s motives."
He can claim the assassination was an official act in defense of national security, and no amount of "but he owed the guy money!" matters.