Should I report unprofessional behavior through the Chain of Command or an IG complaint?

I would break this down into a few different issues rather than respond to the whole thing in one shot, as I see three different behaviors here that could be of concern.

First off, cursing / loss of bearing. Most officers at one point in their careers have encountered situations where they have lost their bearings. Sometimes it's deserved, even if it's not the most effective means of correcting someone. I used language like that one time to an E6...after he was caught doing drugs in the barracks with his subordinate troops. I don't regret it. I believe GEN Mattis once lamented on the use of cursing to get troops attention and put added emphasis on a statement. I don't have an issue with cursing in general, but it's like many other things, in moderation it's okay, but not in excess. That type of cursing in a dress-down in front of an audience is bad judgement regardless.

Second behavior...degrading the NCO. There's a difference between cursing while correcting someone, and what is presented here. This was not a correction but a tear-down. There are exceptions to the rule, but 99% of the time this is toxic to the unit and shouldn't be tolerated. If the recipient of the tear-down did something that was so absolutely egregious (rape, dealing drugs to troops, other serious felonies, etc) to where he's on the short-track out of the service, then maybe I wouldn't make a huge deal out of it, but it should have been behind closed doors, and done by the CDR. If this wasn't the case here, and I don't get the feeling it was, then it was absolutely uncalled for and accomplished nothing.

Third behavior...the CPT smirking and telling others she ripped the guy after the fact...and doing so in earshot of others....uncalled for and unprofessional, regardless of the backstory.

So, long story short, there's enough of concern here regardless of the history that I'd recommend doing something with it. I'd recommend bringing it up to the CSM if you're enlisted. CSM will most likely bring in the Bn CDR. The Bn CDR will have a more complete picture of the CPT and is in the best position to determine if the Army is best served by correcting / mentoring the CPT, or if the situation merits a 15-6 investigation with potentially more severe repercussions.

If I were that CPTs supervisor, would pull that officer aside and give her the run down on how officers under my command are expected to act. She would be in my office, standing in front of my desk at the position of attention. I'd tell her that her conduct is well be low my expectations of an officer of her rank and that her decorum is severely lacking. I'd go on to say that if she didn't like what I was saying then she could take her objections up the chain of command and that I'd be happy to provide the next commander in the chain a letter explaining the situation. As a matter of fact, I'd offer her the opportunity to call my commander and that I'd be happy to dial the phone for her. Finally, I'd provide her the opportunity to excel by having her come to my officer for a couple of Saturdays so that I could properly train her in professional courtesy and bearing.

That behavior, right there, needs an immediate correction. "Ma'am, will you please join me in the hall?" Followed by "Ma'am, would you please accompany me to discuss this with the commander?" Followed by "Ma'am, if you choose not to accompany me...I'll ask the Chief Master Sergeant/Master CPO/Sgt Maj/First Sgt to find you. If you still won't accompany us voluntarily, then we will have the discussion without you present."

The conversation in the room is to discuss the history and the job of a SNCO. I was a similar situation and had a frank/respectful discussion the commander the situation and at the same time held myself accountable while holding the commander responsible for his officers. "Sir, I understand my rank and what is expected of me...have I failed in that? If I have, then maybe we need to discuss future role changes or remedial training. If not, then it is NOT possible for me to lead my soldier/sailors/airmen/marines, when this is how the O-3 belittles me publicly. This is not the first time it has happened and it appears to be a personality conflict. If so, I'd like to fix this now. This destroys the trust and bond that I have formed with my men and women. It will be impossible for me to carry out my duties. In addition, this is an officer. She is an example to the junior enlisted. If she mistreats her SNCO's publicly, then the NCOs and junior enlisted will think that behavior is tolerated or encouraged. She sets the example, and she is not performing as an officer and a lady."

An O-3 is an officer and the rank must be respected. But there is a delicate balance there for that O-3. If she insults the SFC publicly, the effect is pretty poisonous to an organization. Both, the SFC and the CPT, will pay for this. Some will take sides and unit cohesion suffers. The Colonel/CAPT will be very interested on making sure that this doesn't happen.

Expect and apology from that Captain.

The SFC should go to his First Sergeant, who should in turn take the matter up with the Battalion Sergeant Major. Let the Sergeant Major bring to the battalion commander's attention the conduct of one of his officers. If everyone is doing their, jobs this will be your best remedy. If people start putting their careers over the care of their soldiers, in the long run everyone is going to suffer.

If you look at the typical IG charters, personal conduct isn't in their swim lane. Besides the IG has no line authority. If they get the complaint, they shove it over to the CoC. Problem is it gets shoved over to the front office hence bypassing much of the CoC. Nothing like having the front office ding downwards on this stuff catching some good NCOs and JOs off guard who might have been your best advocate. A good SEL should make sure all the ENLs understand the complaint redress process and what goes into what puka. You don't want to become the problem by working the system sideways. BTW, thinking back on things, 2/3rds or more of the officer/NCO job firings I did were over personal conduct, i.e. they treated people like crap. Great morale booster overall when you trim the bad apples.

I am truly amazed by some of these comments that are being posted by STAFF SERGEANT's and above. NCO's begin their comments with, I don't know what regulation covers this and that, or not sure if the CPT's actions are justified.. I don't care who you are nor do I care what Rank you are, you do not have the right to disrespect Soldiers or NCO's for that matter. And the SSG that initiated this post, why are you posting this when you should be reporting this???

Okay, while everyone tries to come up with "appropriate" ways to handle this I'll relate a sort of kind of similar experience and how it was handled. A LTjg (O-2) said to a PO1 at quarters before the CO and XO showed up "Did you roll in the mud this morning? You are a disgrace. How did you make 1st class?" The first class popped to attention and yelled out (think of boot camp) "SIR ! I have no clue how I made 1st class petty officer being the disgraceful piece of sh*t I am that got dragged up here while working on a piece of equipment that has to work or we don't go to sea and the captain would be in hot water for missing an assigned deployment. SIR!"

Yeh. LTjg didn't say much after that.

I would definitely go directly to my chain of command right after I render a proper salute and exit stage left. My 1SG will be informed, and then on. It's one thing to give me a well deserved a** chewing behind closed doors. But once you cross that line of professionalism, and use profane language towards me, you are being out right disrespectful, regardless of what rank either of us is wearing. And then to even think about mentioning my family.....when a "leader" uses their personal feelings towards a fellow Soldier, they are no longer, at least in my opinion, a leader.
So, if going to the COC does nothing, then my next step is IG.

First and foremost, I tip my hat to this NCO for maintaining his composure and bearing. A sign of a true professional. I, personally, would first address this situation with my 1SG and BN CSM. I have yet to meet a CSM that would just let something like this slide. I would almost guarantee this CPT would have an appointment with the BN Commander very shortly after.

This is typical of someone who has been promoted beyond their professional ability, it seems to me it is all about power and a "what are you going to do about it" attitude. The best type leaders are actually servants to their troops (doing their best to uplift them, and motivate with wisdom). It is most unfortunate when vindictiveness is elevated beyond the general welfare of the troops, but not uncommon nowadays. It is not uncommon in my experience that many junior grade officers feel they need to "prove something" about who they are (so to speak) by tearing down another within the "pecking order" of the garrison. Yet this could be quite deadly when one's life depends on upon unit cohesion within the company say while in harms way.
I have also seen NCO's have officers reprimanded for "unbecoming behavior from an officer", but it must be done precariously and precisely via proper channels.
I was once asked to testify by my direct officer, about the behavior of another officer in my unit, but was advised not to do so by my first sergeant - because of repercussions on me under the UCMJ.