I read the Uniform Code of Military Justice when I was in the Navy.  It not only allows service members to refuse an unlawful order – it requires us to.

Obeying an unlawful order is a crime under UCMJ, and no, “I was only following orders” is no defense.  We already settled that, at Nuremburg….

“I was only following orders!” isn’t a defense, it’s an INDICTMENT.