Cal. Probate Code § 16465

(a) Except as provided in subdivision (b), if the trustee, in breach of trust, enters into a transaction that the beneficiary may at his or her option reject or affirm, and the beneficiary affirms the transaction, the beneficiary shall not thereafter reject it and hold the trustee liable for any loss occurring after the trustee entered into the transaction. (b) The affirmance of a transaction by the beneficiary does not preclude the beneficiary from holding a trustee liable for a breach of trust if, at the time of the affirmance, any of the following circumstances existed: (1) The beneficiary was under an incapacity. (2) The beneficiary did not know of his or her rights and of the material facts (A) that the trustee knew or reasonably should have known and (B) that the trustee did not reasonably believe that the beneficiary knew. (3) The affirmance was induced by improper conduct of the trustee. (4) The transaction involved a bargain with the trustee that was not fair and reasonable.