In answer to the original question, it is ethical to do whatever is necessary, without violating the rights of others, to free oneself from the clutches of a criminal state which has broken its Constitutional chains. Just the same as it would be perfectly ethical for a black African in 1750 to kill his slave trading captors in order to escape, since someone who attempts to enslave you has no right to do so and continue living at the same time. You have a right, if arrested by agents of the state, to speak to your lawyer and to all due process, not to mention a speedy hearing before a judge, followed by a trial. You have a right to know what you are being charged with, too, and who your accusers are, and to face those accusers in open court. If denied those rights, the state has, in essence, declared open war on you, and you have a right, ethically speaking, to respond in kind.
The only exception would be a prisoner of war, but if there has been no war declared by Congress, that's impossible. There cannot be a limbo status which falls between the cracks called "enemy combatant." The principles laid out in the Constitution refer to relations between people and government in general, not only between American citizens and our government, therefore the Federal Government was never granted powers to treat any human being as though he had no rights.
In referring to the exception of prisoner of war status, it was not my intention to suggest that this is an exception to the right, within ethics, of attempted escape. If your nation is at war with the nation which is holding you captive, you are still in a state of war with your captors, and are ethically within your rights to do what's necessary to escape, even kill. The exception which I refer to is that regarding the government's obligation to provide you with an attorney, knowing the charges against you, etc..