How would you react to an E2 who "smart mouths" you in formation?

Today's military? or 35 years ago when I first entered ? The answer definitely would not be the same.

In my day, in the Vietnam era: drop and give me 50. Then article 15 with a few weeks of KP duty

If the infraction was in public, address it in public.
Immediately issue commands:
Group-attention, half-left face, front leaning rest position move.
Now that I have your attention,...
Explain chain of command, leadership positions, how every one of them will be in your position in the future, then go into explaining insubordination.
After 10-20 four count push ups, inform pvt shithead that he will stand fast once everyone is dismissed, everyone can personally thank him for the additional physical training later at their convenience.
Once assignments are identified and the unit is dismissed, immediately go full on drill sgt about lack of respect and insubordination loud enough for others to hear. Direct pvt shithead to stand at parade rest in front of the 1SGs office, double-time, and wait for you.
Consult with 1SG behind closed-door, while shithead waits, to discuss options of counseling statement or AR15.
You need to take immediate action and send clear message to entire unit that such behavior is unacceptable and will not be tolerated.
Been there, done that, positive results.

In formation?!!! Maximum punishment you can deal out.....don't want any of his Buddies to think they can do it and escape consequences!

Had it happen from an E3. He kept saying bs & intentionally getting out of step, saying this is all bs. I gave 2 warnings to him while marching, then halted the formation, left faced everyone, told him in a very calm manner if he keeps any of this up, I'll see he loses whatever rank possible & is fined the max allowed for every violation I could come up with, directly impacting his wallet & I have around 40 other witnesses standing next to him. He was not a problem after that. I forget where we were going but it was a bit of a long march. It was at NCO training/school, so I just now wonder if it was a test, this was 40 some years ago.

I think that today’s soldiers lack an understanding of how badly insubordination can go, I have seen a number of posts that would illustrate how the situation would be handled in my day. I even got to witness how my NCO’s dealt with it, it was not very pretty.

DROP!!!! Start pushing the ground. I then turn to the section leader and have him drop alongside the PV2. After 2 minutes I tell the section leader to get up while PV2 Dipshit is still pushing as I enquire why a PV2 is being so out of line. I give the option to the first-line supervisor to handle disciplinary actions (delegation of authority) and inform him/her that I want a complete briefing on corrective actions applied. If the attitude continues the actions will become much more severe with even the possibility of Article 15 and separation.

Really, back to this subject again? If you have a smart mouth in your squad, platoon, company, etc. Just give him/her a blanket party or the worse details for them to complete by themselves. Extra strenuous PT would also be in order. But people, please get on with another subject.

I would simply note, old thread that this is, that it isn't an officer issue. I used to go to Cp Pelham in the ROK every time one of my drunk-ass troops was policed up by the MPs in the local ville. The theory was (and it proved out) that if the Troop Commander showed up personally to get the lad in the middle of the night, the MPs might lighten up on the blotter entry. I ALWAYS took the 1SG (who relished even less than I did jeeping over to Cp Pelham from our Cp Garry Owen. After we got out of the gate of Pelham, Top Daly kicked the drunk-ass troop out of the jeep and we slowly wended our way back to Cp Garry Owen with the troop trailing behind, stopping occasionally to "clear his system of the dog that bit him." When we were sure he was emptied our, we piled him back into the jeep and picked up the pace. When we finally got back to our Cp, I'd ask Top ... anything you need me to do on this one? Invariably, the answer was "no sir, I've got it." On the [rare] occasion that I asked what he did, he told me "sir, I made him an integral part of my wall locker." That method of administering justice probably wouldn't float in these days of "safe space" and "feel good" ... but it sure saved a lot of troops from getting an adverse mark on their records ... and some of them went on to be fine NCOs in our Army. To the issue in this thread ... IMV it is purely an NCO issue ... and no higher than E7 at that. Don't wake me up for it.

Tell him in private that he either obeys orders or faces disciplinary action either as Art. 15 or Courts Martial for disobeying a lawful order. The choice is his.

To paraphrase1 of my NCO's from 3d Batt (Ranger) in the 80's, a great NCO who taught me a tremendous amount, he would be pushing Georgia down to Florida! In addition, since you say it was in formation, & therefore a public challenge to authoroty & discipline, I would sacrifice my Sat to spend time with him improving his military discipline. My 1SG in 3d Batt regularly held "School of the Soldier" on the weekend for those who had screwed up.

In the old days(I enlisted in '71) it would be squad punishment-sometimes pretty hard stuff. Then if the guy had a blanket party....
I don't think that stuff happens now.

Put the mouth in front leaning rest. Explain to him that if you assign this to another sailor, the mouth will remain in this position until the other sailor returns. Do you want to rethink your response? You can also lock his heels, and explain to him that he can stand right here until the job is done, and do not send anyone else to do it, but that depends on how long you have to play that game.

Brown Boot response or MVA response?

50 years ago this would not have happened in the Marine Corps. You were conditioned to do what you were told to do. You carried out the command or you would stand tall in front of your chain of command. I've never seen this happen.

Start with a summarized article 15. Taking his time away for wasting everyone else's time might set his attitude straight, if that doesn't work you can always escalate it

The answer I'm supposed to give, by current rules and regulations, is that I would counsel the SM after formation, and continue counselings until either SM learns to do as they are told or SM is involuntarily discharged. My real answer is that Soldier would end up either strong or smart. Do as you are told immediately or beat your face 'till I am tired. Granted, I'm Combat Arms, disobeying orders in the motorpool is as serious as disobeying orders in a firefight. There is a reason, other than just time in service, why I am a Staff Sergeant and that Soldier is a Private.

Direct order then artical 15

March the scitbird straight up to the 1SGT (a 1SGT with gonads) explain what disrespect entails, remind scitbird the he/she is in the Army, transcribe onto a singed counseling statement and set the pace for the next idiot act scitbird does!

Have the entire flight hit the deck and 50 pushups