“Exceptio probat regulam” is a Latin legal maxim that means “the exception proves the rule.” This phrase is used in legal contexts and has a historical origin. The principle behind it is that the presence of an exception implies the existence of a general rule.
In legal terms, if a specific case is considered an exception, it suggests that there is a general rule from which the case deviates. The maxim is often used to argue that the existence of an exception reinforces the validity of the rule in other cases.