This maxim literally means that an action does not arise from an immoral cause.
According to the law of torts , the damage sustained by the plaintiff must be a legal damage or the injury must be a legal injury . When the damage or injury is sustained in any immoral manner no cause of action arises in favour of the plaintiff .
As for an example , if A is infected by B, her paramour, with a venereal disease, the existence of which was concealed by B, A is not entitled to sue B, because an action does not arise from an immoral cause.
The famous leading case on this maxim is Hegarty V Shine .
It may be noted that the plaintiff is also a wrong –doer is no general defence because in that event absurd consequence would follow . Winfield cited an example , to express this absurd consequence , that if A stole a bottle of whisky from B , the latter would not be able to maintain an action, if it turned out that B had purchased the bottle on a “dry” day .
One of the well established maxims of equity says that he who seeks equity must come with clean hands. This does not mean that the plaintiff should be absolutely spotless . In the words of Sir Frederick Pollock, the plaintiff will not be barred from suing unless “some unlawful act or conduct on his own part is connected with the harm suffered by him as part of the same transaction.”