What do you do when a soldier refuses to listen to your directions?

1) if the soldier has been wearing them for a while now, then there's been a lack of leadership.
2) if it's his first time I would stand him at attention do a uniform inspection, politely take them off his face and have him come get them after formation.
3) if this persist then I would smoke the shit out of him/her until their arms are so week that they can't pick up their arms to put on the sunglasses.
4) last ucmj action.

You snatch said glasses off soldiers face and destroy them with a vengeance. This not only corrects the problem, it establishes a standard to all the other soldiers. 1: do not violate established standards, 2: I, as you first line supervisor will or be tested, corrections will be handed out immediately and without reguard to rank, creed, or color.

Article 91: Failure to obey a lawful order. It's as simple as that. One does wonder how a soldier has become so disobedient in the first place?

Shoot the basterd in the foot.... if he don't get the message, the rest "_will

I physically assaulted him, I was a specialst with a mission to keep the game in play.
My NCOs were already BUSY and trusted ME to get things done.
AND EXTEREMLY CAREFULLY avoided any unnecessary details ....like 4 times really ,nothing broken.Pressure points were fine.

Counceling ,statements, if properly used, is an effective tool. Since the Army has become a softer gentler Army insubordination is routine and common, but can be delt with. A track record has to be established and then you can do somthing but on a counceling statemenet you can can recomend UCMJ actions if you statement the UCMJ properly. Todays Soldiers are smarter and NCO's advanceing through the ranks at record paseses ar lacking the "Common Core Training" to be an effective leader.
Insubordination is in AR 600-20 but you need the 1SG support.

Give him the option of it going down on paper or smoke him.

Unless you are still in boot camp, punishing the whole unit is inappropriate in my opinion. Boot camp is over, now dealing with Marines not recruits. Calmly let him know that you are giving him a lawful order that will be backed up with the UCMJ which may result in them losing pay and rank which means now doing jobs you used to have to do but don't because of rank. Article 136 was it, the catch-all article. Also remind them that though they think they can get away with the sunglasses issue, but they should think about how people get picked for less-desirable activities.

First off Has anyone thought maybe to sit down and ask if has a problem and if you could Help or someone else can. The Second thing explain to him if he doesn't listen to you than I would put it in Writing and if it CONTINUES I would recommend a AR15. I had one troop back in my day did that very thing and He is Now outside with general Discharge.

I'm not sure if I have already replied to this question before I will have to go back and check. But today is a new day and if he/she is refusing to fallow Lawful Orders, to me it sounds like he or she doesn't want to be in the Army anymore and I would help them by recommending Office Hours for him/her to your O.I.C. and of course there will be 5 or more other charges tacked on to. There are Plenty of Soldiers that want to be there and make the military it their life hence the name "Lifers" they don't need someone there sucking the wind out of everyone's sails by being a shit bird. Plus We are in a Downsize mode so that Soldier sounds to me to be nothing but Dead Weight that needs to be cut loose. Hell is Hard enough for those that Eat, Sleep, and Breath The Military Like and Have it running in their body like Blood to stay in now a days. So why not Make some room for another Lifer to move in.

892. Art. 92. Failure to obey order or regulation
Any person subject to this chapter who- (1) violates or fails to obey any lawful general order or regulation; (2) having knowledge of any other lawful order issued by a member of the armed forces, which it is his duty to obey, fails to obey the order; or (3) is derelict in the performance of his duties;
shall be punished as a court-martial may direct.