When one goes back to the original rape charges against Polanski. What one comes up against is that it really is a she said he said situation.
One could see the mother of the victim, essentially setting things up, expecting that something sexual would happen that would advance someone's (her's or her daughter's) career, and then just leaving her 13 year old in this house, and also see the 13 year old as thinking that she was much more mature than she was and thinking that she could control things, but having them get out of her control. The problem with these kinds of discussions is that they move along and all of a sudden it appears that one (I) am giving Polanski a pass for violently raping a 13 year old. No.
One though is that everything went much farther than either the girl or her mother intended. If, however, at any point the girl was crying and begging him to stop as she said then he is a rapist.
As far as her unchanging testimony is concerned as proof of what happened, I have had clients who have told me obvious lies and then will not get off the story no matter what evidence I can show them to show that they are lying. On the other hand the fact that a witness makes a statement immediately after the incident and continues to hold to the same version of events, is an indication and can be used as an indication that the statement and testimony at a later date is accurate.
Polanski's admissions are really something that more or less innocent people do all the time. The prosecutor way over charges and then dismissed a lot of the charges if you will plead your guy and will give him a conviction and save him a trial. There is even a term for it: Alfred Pleas. Make the case go away with as little pain as possible to everybody. From everything he said he thought of it as consensual. The attitude toward adolescent sexuality was different at that time. also the attitude toward drugs and giving them to quite young people was also different. That's the point of the Pretty Baby link on the last post.