In Durell v. Sharp Healthcare (2010) 183 Cal.App.4th 1350, the Court said a plaintiff could not properly seek recovery for unjust enrichment or restitution, where instead an enforceable express contract relationship existed. However, a cause of action seeking restitution can be based on other underlying theories, such as where a contract was procured by fraud, or "'where the defendant obtained a benefit from the plaintiff by fraud, duress, conversion, or similar conduct.'" (Ibid.)