Killing citizens without court order is also illegal. And waterboarding in gitmo. And starting wars based on lies. And lying to congress by NSA. So many things are illegal, but those who are in charge of enforcing justice are doing them anyway.
Not if you just brand them the label 'Enemy combatants' - laws no longer apply then, apparently. I'm still waiting for someone to accuse and convict the US of war crimes and the violations of the rights of prisoners of war.
[1] Obligatory XKCD http://xkcd.com/538/