Sentence:  After all, Cave speaks about orders being so manifestly illegal that the person carrying them out must or ought to have been aware of their unlawfulness. From this alone, one can draw the conclusion that, if the <WSD>executant</WSD> of the order actually knows of its unlawfulness, he ought to be convicted, no matter whether the order is or, as in John Doe's case, is not manifestly illegal. 
Meaning of the word marked with <WSD> tags:  A person who puts something into action, such as a plan or design.