This is an interesting thing about batterer's intervention programs in the state of Massachusetts. I recommend that you check it out! Of particular interest, though not mentioned on the Mass.Gov site, is the fact that in order to begin a batterer's intervention program, the perpetrator must confess to the abuse. Not just "my partner/ex claims I did X," but "I did X, Y, and Z to my partner/ex." Treatment only works when the perpetrator is actually working on it. It's not a process one can lie their way through. Which is why the success rate is high (see study info on that site). And which is also why, if a perpetrator is attending a program of this sort, they might take measures to keep their victim from stating that they're doing so: it is an admission of guilt. Obviously this is the second-most-desirable outcome in an intimate partner violence/sexual violence case - the most desirable, of course, being jail time, but a) that's a different system, criminal rather than civil, and b) only 6% of rapists ever go to jail, and that statistic includes *all* rapists; it's much lower for rapists who were in a relationship with their victims, who only rarely even get arrested, let alone tried and convicted.
Obviously, as someone who's been speaking about sexual violence on The Internets since 2002 and who's been volunteering at their local rape crisis center since '08 - go BARCC! - this is stuff that is of interest to me. People who've known me for a while will also recall that I've been planning to write a book about how to dismantle rape culture in your free time. That's mutated a bit, and will now be more about intimate partner violence; I feel like that's a useful place to focus, given its prevalence in the number of incidents of sexual violence and its shockingly low rate of prosecution. That'll be my summer/fall nonfiction writing project. I might post a few things like this here and there as my research continues. I look forward to telling you lot more about it in January.
(Comments closed for now because my parents, sister, and niece are in town and monopolizing my time; I only get ~5 minutes at a computer every day, and thus cannot moderate.)