Polanski was initially charged with rape by use of drugs, perversion, sodomy, lewd and lascivious act upon a child under 14, and furnishing a controlled substance (methaqualone) to a minor.
The grand jury transcript describes the alcohol that Polanski allegedly supplied before engaging in oral, vaginal and anal sex with the 13 year old girl, who repeatedly no to Polanski's sexual advances.
This was rape proper, after the girl had been drugged with alcohol and quaaludes. However, in a plea bargain Polanski pled guilty to simply unlawful sexual intercourse with the underage girl and was awaiting sentence when he fled to France.
One has to take in the context of the time. In 1977, child sex was a hot thing among the rich & famous. Half a dozen child porn magazines were in international distribution, mainstream Lolita films were being shot by studios (i.e. Pretty Baby), porn companies would rent adjacent hotel rooms. In one room a legal hotty was having sex and in the adjacent room, a 10-11 year old was having sex with a boy and/or man. Finally, stage mothers were having their preteen daughters pose in mainstream magazines. 12 year old Eva Ionesco posed borderline X rated in French Playboy and 12 year old Brooke Shields posed nude in a photographer's magazine.
Roman thought he was going to use the old casting couch on the girl, but it went all wrong. Then, like some Hollywood folk, he was surprised when he was going to actually be held accountable for his actions-so he fled.
Normally, this case would've disappeared in the statute of limitations, but several years ago, California, like some states, did away with statute of limitations on child sex crimes. His arrest will most likely turn into an exercise of futilism and he'll return to France after some legal arguments take place.