California Code, Probate Code - PROB § 10162

(a) Subject to subdivision (b), where the bid returned to the court for confirmation is made by a person who is not represented by an agent or broker and the successful bidder is represented by an agent or broker, the compensation of the agent or broker who procured the purchaser to whom the sale is confirmed shall not exceed one-half of the difference between the amount of the bid in the original return and the amount of the successful bid.

(b) This section does not limit the compensation of the agent or broker who holds a contract under Section 10150 granting him or her the exclusive right to sell the property.