Or not unless no disabled actor is available who can play the role (as might be the case with a severe disability or amateur acting).
This video: www.facebook.com/disabilityonthemighty/videos/1395870050538459/
has been doing the rounds among my thespian type friends on facebook and I think it makes a lot of sense.
(in summary it says that 20% of people are disabled but only 2% of characters on tv have disabilities and 95% of those roles go to able bodied actors leaving very few opportunities for disabled actors. It compares old practices of casting white actors to play black characters and says that able bodied actors playing disabled characters should be equally avoided nowadays).
It's getting a lot of positive attention but some people are saying that there's no point in acting if we only get to play characters like ourselves and that some actors have given brilliant portrayals of disabled characters (Leo di Caprio in What's Eating Gilbert Grape comes up a lot).
I do agree with that point but I think there are enough challenging roles out there for talented able bodied actors without taking the few roles available to disabled actors. I don't think they should be allowed to have the roles unless the casting director/director has tried and failed to cast a suitable disabled actor. AIBU?