It is now, private Schools were the last ones to get rid of it, I think it is still legal, in some other Countries!
In some US states its legal still. I went to a Catholic private school in the UK, they stopped in when it was made illegal everywhere in the 1980s (except parents) . They just dumped other punishments on us, like making us pick up litter outside, a random cross country run, writing out a prayer in Latin 100 times.
My mother was beaten by nuns as a girl, and she has had a fear of nuns, and hasn't been able to feel safe about criticising the Catholic Church, ever. That's not healthy. For her early years being beaten by those nuns, she has been unable to feel independent. Corporal punishment is a way of saying that you have nothing to say, resorting to brute strength because you're not actually in the right. That breeds a terrible attitude towards authority, and beaten children often turn into abusive adults.
But did they really turn out ok? I would say no, they didnt. Most adults these days suffer from so many mental health issues and id bet a lot of them are because of childhood trauma, ie their parents chosen style of punishment. My dad has anger issues that I believe stem from his fathers disciplining, But he rationalized it to us by saying its ok im not using a belt or anything like I got when I was a kid so your getting off easy. Then there is my mom who is way fucked up because of her parents abuse and lack of good parenting skills. I always hated the notion that the reason kids these days don't show any respect is because they didn't get beaten. Firstly respect is earned, and then has to be maintained. Kids these days know they aren't getting the respect they want, need and sometimes deserve. Secondly, most of the kids I see acting out have a shitty home life, either because they were beaten or verbally abused etc, or because there parents didnt give a shit enough to raise them right. To me its not the lack of corporal punishment that is effecting our society, its lazy and inept parents who had kids when they shouldn't have and then expect the rest of the world to raise them right.