Soldiers are allowed to disobey orders that are *illegal *(for instance, being ordered to commit war crimes) - but to what extent can soldiers dissent against or disobey an order that is not illegal, but simply utterly disastrous or suicidal (and the commander is insistent that the order be carried out no matter what?)
No official data, but according to friends & relatives in the US military:
First, you really better be right (that following the order would have been disastrous).
Second, it better be obviously right (so that afterwards, everyone up the chain of command can see that following that order would have been disastrous).
Third, whatever you did instead should have had a clearly better result.
If all of those are true, then the order (and your insubordination) will just be quietly forgotten.
Note that this is disastrous in terms of the unit and their mission. Disastrous to you personally, or suicidal isn’t enough – it’s not uncommon for officers to give orders that are dangerous or even suicidal to some of their troops. That’s kind of the definition of military.
Wasn’t this the whole idea behind The Caine Mutiny and also Paths of Glory?
The latter IIRC was based on a real incident. Paths of Glory - Wikipedia
According to lore, the Austrians gave you a medal if you were successful. If not you were left in a room with a loaded pistol.
Well if the order was suicidal, I’d rather spend my life in prison than dead.
I spent 24 years in the military. Most orders aren’t all that important. I’ve asked to have orders clarified. I’ve argued respectfully about some orders. I’ve asked to have the order put in writing. When all that failed, I’ve followed orders. Sometimes the best way to get rid of a bad officer or senior NCO is to follow their orders exactly.
We had a saying in the army, “Tzalash o tarash”, which translates as “medal or PFC” - it means a situation where, if you succeed, you get a medal, but if you fail you get knocked down to Private First Class. Disobeying a stupid order is often one of those situations.
The US Army’s current doctrinal answer to the question, from ADP 6-0 Mission Command.
“Suicidal” may or may not pass the test of needless risk. High risk of death in a specific subelement may still be needed to accomplish the overall mission and reduce risk to the force as a whole.
One case from World War II is a Lieutenant Colonel who disobeyed orders twice in a span of a couple hours in order to relieve Bastogne (link to pdf). The link is to an entire issue of a professional journal with an article title that included “Knowing when to disobey orders.” In that case the officer in question was awarded his second Distinguished Service Cross and a couple months later he was promoted to Colonel. He eventually became Chief of Staff of the Army and had a tank named after him. He was Creighton Abrams.
By Auftragstaktik (with it’s current US doctrinal name of Mission Command) leaders should issue orders that focus on the goal to be attained with a minimum of restrictions necessary. Colloquially I like to think of it prioritizing the why of an operation over the what, and the what over how. If the what or how are no longer applicable or riskier than another option to achieve the overall goal, Commanders SHOULD disobey that order. That can still make lots of officers who haven’t internalized Auftragstktik get all freaked out.
[nitpick]Not exactly. The Caine Mutiny centered around whether the subordinate officer was right in relieving his captain as unfit for duty. If Queeg hadn’t gone catatonic but had remained on his feet and insisted on maintaining course, then it would have been an example. And in Paths of Glory, it was that a major portion of the French Army decided that it had had enough and wasn’t going to fight at all- I think that’s a bit more than disputing a particular course of action.[/nitpick]
The Caine Mutiny was also based on a real-life happening - the sinking of USS Hull during Halsey’s typhoon.
When Hull was in bad trouble, crew members reportedly urged the executive officer to take control of the ship to remedy the captain’s alleged failure to take proper action. The exec (who later died) is said to have remarked that if he tried it, he’d be found guilty of mutiny.
I’m sure you know but others don’t that ADP stands for “Army Doctrine Publication.” Doctrine is not regulation or law. We are talking about guidelines rather than UCMJ.
And the doctrine you quote is for commanders. The commander on the ground doctrinally has more leeway in the heat of the moment to deviate from his OPORD. He is the one who knows the situation fully. Even at the Field Grade level a commander has the responsibility for his troops. U.S. doctrine allows for a certain amount of autonomy of action in lower level commanders. Something that the Soviet model does not provide for.
But the OP asks for what the individual soldier can do to disobey an order that he deems disastrous. Doctrine does not address that issue. That is a UCMJ issue.
Most likely apocryphal:
"One of the serious problems in planning the fight against American doctrine, is that the Americans do not read their manuals, nor do they feel any obligation to follow their doctrine…- " Soviet quote
I read of a Army Cobra pilot in Vietnam who, when ordered to enter a rather narrow valley and investigate the location of 4 radar guided quad 50 machine guns, replied with “bite me.” Self preservation is a strong motivation for using common sense. Apparently nothing happened thereafter due to all the confusion. But then Army helicopter pilots in Vietnam weren’t on the *career *path either, so to speak.
In confusion there is profit and safety.
And Bruce Crandall and Ed Freeman flew into LZ X-Ray when the ground commander closed it and the MEDEVAC commander wouldn’t put his helicopters into the area. But he knew the 7th Cavalry needed supplies and evacuation of the wounded. It took till 2001 for Freeman to get his Medal of Honor. Crandall had to wait till 2007 and he was only promoted once after being seen as a trouble maker.
Alternative option:
(From this: Red Bull Rising: Vietnam to Today, 'Doonesbury' Tells Soldiers' Stories )
Under the reorganization (with all the new naming schemes) ADPs are “authoritative” as opposed to things like ATPs (Army Technique Publications) which are "non-prescriptive. Cite in PPT While judgement needs to be applied it’s more than simply guidelines. They are required guidelines unlike some other aspects of doctrine. It’s just harder to judge compliance than it is with regulation since it’s not as clearly black and white.
Interesting aside - no commander I’ve ever met complied with every regulation either. Those that claimed they did conceded my point…usually after my first question. Their commander knew. 
Commander’s are still Soldiers so it’s part of the puzzle. 
Let’s show a little love for the company grade commanders while we’re at it too. They have full legal authority. More importantly there’s a bullet that covers a good chunk of the same space for those that aren’t commanders. Before the part I quoted is:
The language related to the risk exception is less robust than the language for commanders but there’s still some parallel. The exception for the orders no longer fitting seems to be functionally the same. It’s still right to disobey orders to achieve commanders intent. For the kind of order we’re talking about you’re likely looking at an Article 92 violation and needing to show a “duty to obey” as an element of proof. There’s no clear connect that I am aware of with disciplined initiative overriding that piece (like unlawful orders do). It’s an interesting piece that I wish I was still in boots to wander over and harass the SJA with. I know I’d bring up ADP 6-0 if I was an investigating officer in a case where someone exercised initiative when looking at the “duty to obey.” If it truly was initiative within intent I personally couldn’t recommend punishment.
I firmly believe that’s one of the reasons they made the ADPs with a target of 10 pages in length. With only fifteen of them you can get the key principles of Army doctrine in 150 pages. It’s STILL hard to get busy leaders to read that deep. That issue is where someone could still get hemmed up with a poor commander issuing a horrible order. That commander likely isn’t exercising mission command and has strong administrative powers to cause issues even without invoking UCMJ. That can get ugly depending on the chain above the poor comannder in question.