Heated exchanges, raised voices and the visual of a mostly male, uniformed military command playing defense set the tone for Tuesday’s Senate Armed Services hearing on sexual misconduct, but three pivotal moments ultimately could define the Senate’s larger policy debate on the issue.

Several senators have introduced bills aimed at curbing military sexual assaults, but only a limited number of provisions will end up in this year’s national defense authorization bill. Moreover, it’s clear that the armed services top brass is uncomfortable with significant changes to their centuries-old focus on the chain of command, despite a record 26,000 incidents of sexual misconduct in 2012 estimated by the Department of Defense.

The military’s top decision-makers acknowledged Tuesday the status quo is a problem but could not imagine a system other than the one on which they were trained — a key tension that could shape congressional debate on the issue indefinitely. Clues to the fundamental obstacles and key drivers of change could be found in the following three moments.

1) Sen. Joe Manchin III, D-W.Va., gets leaders of the Army, Navy, Air Force and Marine Corps, as well as top brass of the Joint Chiefs of Staff, to admit they do not support removing the sexual assault reporting structure from the chain of command.

That there was consensus on this matter is not surprising, though it certainly was frustrating to lawmakers such as Sen. Kirsten Gillibrand, D-N.Y., who has introduced legislation to remove the reporting procedure for sexual misconduct from commanders’ purview. What was revelatory, however, was the response from Adm. Jonathan Greenert, chief of naval operations, to Manchin’s plea that someone on the panel speak to why none of them supported such a move. Here is what Greenert said, in all its circuitous glory, and it’s at the heart of the problem Congress will have in changing the system (italics ours, for emphasis):

I don’t know how to take it out of the chain of command, and then in the continuum of responsibility and authority that we tell our people that they’re responsible for the welfare — and this goes to training … through combat, all of that — how you take [chain of command] out of it, and then you put the the victim back in, if they come back, or if the report is reviewed, the investigation is reviewed and it’s returned and they say, ‘Well, here you go.’

I just don’t understand how to do that yet. And so, from that perspective, I do agree with General Amos. Because I haven’t been able to internalize or understand it. But as I study the proposals, I don’t know how that works.

2. Sen. Claire McCaskill, D-Mo., calls for better data collection on incidents of misconduct and a disambiguation between violent sexual assault and a culture that disrespects women.

McCaskill, a former prosecutor, made one of the hearing’s most salient points: that reporting “incidents” of misconduct without doing the due diligence to define that misconduct will not help the military solve its current problem. She said lawmakers could benefit from more detailed information as they try to make legislative changes that could assist the military in improving its culture, as well as protect some of the measures that military leaders hold dear.

From McCaskill’s statements before the panel:

There are two problems. One is you have sexual predators who are committing crimes. Two, you have work to do on the issue of a respectful and healthy work environment. These are not the same issues. And, with all due respect, General Odierno, we can prosecute our way out of the first issue. We can prosecute our way out of the problem of sexual predators who are not committing crimes of lust. My years of experience in this area tell me they are committing crimes of domination and violence. This isn’t about sex. This is about assaultive domination and violence.

I want to start with, I think the way you all are reporting has this backwards. Because you’re mushing them together in the reporting. Unwedded sexual contact is everything from somebody looking at you sideways when they shouldn’t, to someone pushing you up against the wall and brutally raping you. You’ve got to in your surveys delineate the two problems. Because until you do, we will have no idea whether or not you’re getting your hands around this. We need to know how many women and men are being raped and sexually assaulted on an annual basis, and we have no idea right now. Because all we know is we’ve had unwanted sexual contact, 36,000. Well, that doesn’t tell us which — whether it’s an unhealthy work environment or whether or not you’ve got criminals. And you’ve got to change that reporting.

Success is gonna look like this: More reports of rape, sodomy and assault, and less incidents of rape, sodomy and assault.

3) Sen. John McCain’s serious indictment of the handling of a problem that he said left him “disgusted and disappointed” with the military in which he once served.

As WGDB reported earlier today, McCain’s testimony was the most dramatic and likely damaging of the hours-long hearing, because of his elevated role on military issues. In previous fights on personnel issues — like the battle to repeal the military’s “don’t ask, don’t tell” policy — McCain almost always has been deferential to commanders. Here, the retired Navy captain and former prisoner of war, went after those same commanders to their faces.

“Just last night a woman came to me and said her daughter wanted to join the military and could I give my unqualified support for her doing so. I could not,” said the former GOP presidential nominee, who is a leader on military issues. “I cannot overstate my disgust and disappointment over the continued reports of sexual misconduct in our military. We’ve been talking about the issue for years and talk is insufficient.”

McCain supporting the Gillibrand measure would be a game-changer, although there’s no indication yet that he would. Still, his impassioned statement helps set the foundation for action of some sort to come.