Some observations

The DA was correct at the beginning; when Murphy told him that she couldn't prosecute the rape he said the perps couldn't walk and to put them away on another charge and he included a lesser rape charge (Rape Two). And during the meeting two of the three defense attorneys went for Rape Two, but instead Murphy let the reputation of the college kid's attorney sway the whole charge by changing it to Reckless Endangerment.

She had them by the balls and should not have backed down. The physical evidence alone would've won a conviction (in my opinion Rape One) regardless of witness credibility.

As for the solicitation charges against the other three, I do agree with her going after them, it's likely Curt (the last rapist aka "Needle Dick") would not have penetrated Sarah if not for their goading him into it. (He still would be guilty of complicity however)

Also, at the end of the film where the judge reads the verdict you see Cliff (Leo Rossi, a great actor) nodding his head as if admitting they were in fact, guilty of solicitation.