Can a person who is considered “normal” date a person who is...

I’m sure it has its complications. It’s Always Sunny in Philadelphia bravely addressed this issue in season 3, episode 9.

It's considered a crime in some states/countries to do anything sexual with someone that's mentally retarded.

Some may not agree with the law but there are plenty of people on sex offender registries right now that sexed-up a mentally handicapped individual. The reason for it being against the law is, these people are considered the same as children mentally, therefore, it's assumed they couldn't actually give consent to have sex with someone.

Shame really, because most people that have this handicap may never experience sexuality in their lifetimes. But... it is what it is I guess and I doubt anyone would challenge the law for fear of being labeled as "some kind of pervert" that wants to sex up the mentally challenged.

https://www.youtube.com/watch?v=KyRHAvfA6Eg