Illegal orders can be refused. But such would be things like orders to rape or murder civilians.
So it is thought that “illegal orders” might just be those that Democrats don’t like. I hope they are looking into this thoroughly. In wartime, we sure don’t need a problem with any possible “illegal orders’ that might not be such. In my 4 years in the military, I don’t recall ever hearing anything about such orders, but I do believe there was a chapter in our handbooks dealing with that. Admittedly it was not wartime, which could well make a difference. If there is some disagreement & questionable orders are legal, then the person or persons doing this should be properly prosecuted.
“Illegal orders can be refused. But such would be things like orders to rape or murder civilians.”
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An order to violate the Posse Comitatus laws would be an illegal order.