It must be mentioned that at common law, an agent must not allow his own interest to conflict with his obligation to the principal. Where such a situation occurs to the knowledge of the third party, the contract is voidable at the option of the principal See Armstrong v. Jackson 2 KB 822; Allied Trading Co. Ltd. v. G.B.N. Line (1985) 2 NWLR (Pt. 75) 74. This common law position is supported by Article 21 of the Rules and Regulation (Exh. AO13) – the Constitution of the Nigerian Institution of Estate Surveyors and Valuers. The interest of the appellant to represent both buyer and seller and claim agency fees from both sides has conflicted with his obligation to the vendor who rightly took the option in my view to terminate the agency appointment. That puts to an end whatever transaction that seemed to be going on between the appellant and the respondent in respect of the property. It would appear that the appellant breached both the Common Law of Agency and the Rules and Regulations of the body he professed to belong to.
— Rowland, JCA. Alex O. Odudu v. Emmanuel O. Onyibe (CA/B/138/98, 15 Mar 2001)