In the version of events most favorable to Kennedy, he suffered a tragic lapse in judgment (failing to summon aid) which compounded the results of an unfortunate auto accident, and a young woman drowned as a result.
The version which is more charitable to the truth and less charitable to Kennedy: He was drunk driving late at night on an isolated road with a young woman who was not his wife. He got into a car accident, which involved his car falling into the water with the two of them in it. After extracting himself from the car, he went home, went to sleep, woke up, talked to his political advisers, then called the police and informed them that there had been an accident.
For normal Americans, that would have resulted in an investigation followed by manslaughter charges. Kennedy was never a normal American. He got off with a wrist slap after pleading guilty to leaving the scene of an accident.
The whitewashing of this incident has always been a stitch in the craw of his political opponents. His political supporters say some variant of the following every time it gets brought up: mistakes were made, it is long in the past, nothing was ever proven, and now is not the right time to mention it.
I'm sort of unsure about the etiquette myself. What's the polite way to say "Ted Kennedy was a man who did many things unrelated to causing the death of his paramour in the cause of protecting his political career"?