(iii) The Agent Must Not Have Notice of the Grounds for a Restitutionary Claim
The agent’s defence will fail if the agent transferred the benefit received from the claimant to the principal once the agent had become aware of the claimant’s restitutionary claim.
(iv) The Agent Must Not Be Implicated in Wrongdoing
The agent will not be able to rely on the defence if he or she had received the benefit as a result of the commission of a wrong to which he or she was a party or where he or she was aware of the commission of the wrong. So, for example, where the agent received money pursuant to an illegal transaction, he or she will not be able to rely on the defence if he or she paid this money to the principal. Similarly the defence will not be available where the agent extracted money from the claimant by duress. The defence is denied to the agent in such circumstances simply because it is inequitable for a wrongdoer, or somebody who has been tainted by the wrong, to rely on such a defence to defeat the restitutionary claim.
-  Buller v Harrison (1777) 2 Cowp 565, 98 ER 1243; Niru Battery v Milestone Trading Ltd  EWHC1425 (Comm),  2 All ER (Comm) 705, 741 (Moore-Bick J).
-  Snowdon v Davis (1808) 1 Taunt 359, 127 ER 872.
-  Townson v Wilson (1808) 1 Camp 396, 170 ER 997.
-  Snowdon v Davis (1808) 1 Taunt 359, 127 ER 872. 75 (1907) 97 LT 263, 264.