The only way to find out whether an order is legal or illegal is to obey, or refuse to obey, and see what is decided after the fact by a military court, a civilian court reviewing a military decision, or a war crimes or human rights tribunal. As a servicemenber subject to the UCMJ, you obey or disobey any order at your peril – which is, of course, one of the risks of enlistment. You can consult a civilian lawyer with expertise in military and international law, but they are very unlikely to be able to give you a definitive answer as to whether a particular order is likely to be found to be legal or illegal.
Good luck....because it has to be blatant. What those ass hats did is skew the meaning of absolute. They were fn' pricks for doing it at the time, but they get it now. No matter what Kelly might say...he knows. He's way better than that.