Oh yes it is. Essentially it says that she is not capable of giving consent, and that any sex with her is rape.
Just exactly what is the difference between the law deciding that she can not give consent for sex and the law forcing celibacy upon her, without her consent?
It depends on the state, and the laws there with in.
It also depends on how intelligent and aware the mentally retarded person is.
I should post it, but in Life News was a story about two Down Syndrome people who got married. Now those two would be allowed to have sex. That would be an example of an exception.
However some persons with Downs don’t understand what sex is because their IQ is so low. To try to do it with them would be the same as molesting a child.
If two supervised (not the act, but parents or caregivers deciding it is safe and mutual) special needs people have sex, no one is arresting anyone.
But neurotypical people should avoid sex with intellectually disabled partners. It just isn’t right. Same as even if a 13 year old girl begs for it. JUST NO.