Cal. Fin. Code § 1451

When the depositor of a commercial or savings account has authorized any person to make withdrawals from the account, the bank, in the absence of written notice otherwise, may assume that any check, receipt, or order of withdrawal drawn by such person in the authorized form or manner, including checks drawn to his personal order and withdrawal orders payable to him personally, was drawn for a purpose authorized by the depositor and within the scope of the authority conferred upon such person.