The defendant has the burden of proof to show the plaintiff is not acting in good faith.
Historically, the doctrine of unclean hands can be traced as far back as the Fourth Lateran Council.
[citation needed] "He who comes into equity must come with clean hands" is an equitable maxim in English law.
The maxim prevents those who have acted improperly in some way relating to the matter at hand from seeking a remedy or relief.
Essentially, anyone with 'unclean hands', someone who has in some way contributed to their own injury or loss, or has in some other way acted dishonourably relating to the matter will be prevented by a court from remedy or relief regardless of how the adversary has treated them.