When is a deed of assignment said to be invalid?

A deed of assignment is said to be invalid if it lacks essential elements such as the consent of both parties, a clear description of the rights being assigned, or if it fails to meet legal formalities required by law, such as being in writing or notarized. Additionally, if the assignor does not have the legal right to transfer the rights or if the assignment contravenes public policy or existing contracts, it may also be deemed invalid. Lastly, if the deed is executed under duress, fraud, or undue influence, it can be invalidated.