Examples
An employee with a visual impairment is dismissed because he cannot do as much work as a non-disabled colleague. If the employer sought to justify the dismissal, he would need to show that it was a proportionate means of achieving a legitimate aim.
The licensee of a pub refuses to serve a person who has cerebral palsy because she believes that he is drunk as he has slurred speech. However, the slurred speech is a consequence of his impairment. If the licensee is able to show that she did not know, and could not reasonably have been expected to know, that the customer was disabled, she has not subjected him to discrimination arising from his disability.
However, in the example above, if a reasonable person would have known that the behaviour was due to a disability, the licensee would have subjected the customer to discrimination arising from his disability, unless she could show that ejecting him was a proportionate means of achieving a legitimate aim.