I know we have a sizable number of posters here on the Dope who are ex-Navy, ex-USAF, ex-Army, etc.
I’m sure you would have disobeyed illegal orders from a US president or commander - but what about your peers? At the time that you served, and a president had ordered the invasion of Greenland, how confident are you that they would have refused? (Not just about Greenland, that’s just one example - you can think of 100 other different scenarios or hypotheticals.)
At what level of illegal order would it have become a blurry area and you and your peers would have really been stuck on the fence and thought, “It’s really hard to tell whether this is an obey-or-disobey situation?”
The 80s, I felt fairly high confidence that illegal orders would be ignored.
When I got to the Ranger, we still had a WWII vet on board. Over 40 years served. He joked his wife was a lightweight and finished with only 30 years. He was our Command Masterchief and went on to be the Fleet Masterchief before retiring finally.
He reminded us somewhere early before moving to our Division berths, that our oath was to the Constitution and not the Captain, an Admiral or the President.
Later, I was given an illegal order to attend a church service and the idiot Jg didn’t understand it was illegal so I went to legal and they backed me up fully.
I’m pretty sure most flag officers and Captains of the time were loyal to the Country and not the POTUS.
In my era (the Reagan years) there would be no debate about illegal orders; they wouldn’t leave the Pentagon. And everybody down the chain would push back if they did somehow get past the big brass.
Nowadays? Beats the shit outta me. We’ll soon see.
When I was serving ('67-'90), the idea of a superior issuing unlawful orders seemed pretty unlikely. It happened in Vietnam, of course, and it would seem that wartime is when there is the most danger of it happening. I mentioned somewhere else on this board that I was given direction once that I considered to be questionable, if not unlawful, and I gently challenged the officer about it, saying that I was “not comfortable with that direction”. He retracted pretty quickly, so obviously he also knew that it was not right.
As to the OP’s question, I’m pretty sure that any NCO would have refused to follow a clearly illegal directive, such as inflicting harm or violating the enlistment oath.
“Any”? I don’t think so. After all, someone clearly did follow the literal textbook example of an illegal order, by shooting shipwreck survivors in the water.