Actually if you look into the case they just didn't have the evidence. People wanted a conviction on moral grounds but that isn't valid in court then or now. Even today you'd have to prove drunk driving otherwise it's an accident. And leaving her there, the moral issue, could be defended as "I had been in an accident and didn't know what I was doing". He was convicted of leaving the scene of an accident. Not defending Kennedy or saying there wasn't shennanigans just looking at the FACTS instead of making [censored] up.