Legal Disability: The Real Issue
In the United States, we tend to understand disability to mean "inability" -- and to understand that inability as innate. Therefore, many of us say "person with a disability" to try to convey that a person is unable to do something, but that this inability doesn't define the entire person.
But we ignore a whole history of the word. Moreover, we ignore the way that this other understanding has been used by disabled people in the United States and elsewhere, and I think we do so to our detriment.