I don't think it's a difference in usage as much as more awareness and activism in one country as opposed to another. Like how the R word used to be used this way in the US and now isn't any more because people have become aware.
Yes. Most people in the disability community would regard it as equally offensive to the R word.
Well, mental retardation is not in the DSM-V, so it's dead and buried along with Asperger's syndrome.
As I have had to explain to clients, "I am trying to prove that your son is mentally retarded. I don't care if you don't like that phrase, because that is what I need to prove. If he is mentally retarded, he wins. If he is not mentally retarded, he loses. You don't get a vote on the words I have to use."
At least I don't have to say that anymore.
I've also had opposing counsel complain about how many times I used that phrase in a brief.
Opposing counsel's brief in that particular case was determined to be somewhat unpersuasive.
