A broker must act in good faith and in the interest of his principal and an agent to sell may not become the agent of the purchaser, nor may an agent to buy become the agent of the seller, unless both principals are fully and fairly acquainted with the fact that the agent was acting in a dual capacity; but if both, knowing the circumstances, consent that the agent may so act, the agreement for commission is valid and enforceable.23

Where a real estate broker represented both the buyer and the seller, and informed the buyer that the lowest price the seller would take for the farm was $7,000.00, when in fact the seller had engaged the broker to sell at $5,300.00, the broker to have all he obtained over that amount, it was held that if the purchaser relied upon the representation, and acted upon it, it was a fraud upon the purchaser; the broker's duty was to disclose the fact that he was acting for both parties and also to disclose all the facts in his possession as to the value of the farm; and in a suit for an accounting the broker was liable for the amount he profited by the fraud.24

20. Holmes Realty Co. v. Silcox. 194 Mich. 59.

21. Smith v. Mich. Realty Co.. 175 Mich. 600.

22. Vaughn v. Sheridan, 50. Mich. 155.

23. Kirby-Sorge-Felske Co. v. Doty, 190 Mich. 533; Hannan v. Prentis, 124 Mich. 417.

24. Moore v. Meade, 213 Mich. 597; Hogle v. Meyering, 161 Mich. 472; Woods v. Palmer, 151 Mich. 30; Phinney v. Hall. 101 Mich. 451.

The broker must act for his principal alone, and a promise by one of the principals in an exchange of real estate, after negotiations were completed, to pay a commission to the other party's broker, to whom he owed nothing, was void for want of consideration.25

Where a broker is employed merely to bring the parties together, and they make their own bargain, thus giving him no discretion or confronting him with a conflict of duties, he may recover commission from both parties.26

Where the broker deals with his principal through an attorney, he is not excused from acting in good faith, nor would lack of diligence on the part of the attorney to discover fraudulent conduct of the broker, active or passive, excuse the broker.27

The contract entered into between two principals is voidable where the broker represented both without the knowledge of one, and the one seeking to avoid the contract need not show that any improper advantage had been gained over him, and he may repudiate the contract irrespective of any proof of actual fraud.28

A broker may not deal with the subject matter of his agency for his own advantage, and where he overstates the price at which it may be bought and obtains the difference, the principal may recover the excess from him,29 and a broker employed to sell property cannot become the buyer thereof either directly or indirectly30