P was mildly injured at work (his left leg became stiffer and weaker) due to D’s negligence, and was later trying to climb a flight of flight of stairs. Due to the weakness of his left leg following the injury, he was about to fall and instead of falling jumped and broke his rights ankle. P claimed damages for the ankle-break but HL refused. HL said D was only responsible for the first accident.
Lord Reid: D should have been more careful following his accident. If a person who is injured does act “reasonably and carefully” given the circumstances of the injury, but is still caused a second injury, then P will be responsible for that too. If D fails to so act (as here- the stair was steep with no hand rail and D refused to wait for assistance), D is not liable for the second accident. “a defender is not liable for a consequence of a kind which is not foreseeable”.