Judging cruelty in matrimonial cases.
“… In matrimonial cases we are not concerned with the reasonable man as we are in cases of negligence. We are dealing with this man and this woman and the fewer a priori assumptions we make about them the better. In cruelty cases one can hardly ever even start with a presumption that the parties are reasonable people, because it is hard to imagine any cruelty case ever arising if both the spouses think and behave as reasonable people.”
Lord Reid in Gollins v. Gollins 1964 AC 644