California Code, Evidence Code - EVID § 765

(a) The court shall exercise reasonable control over the mode of interrogation of a witness so as to make interrogation as rapid, as distinct, and as effective for the ascertainment of the truth, as may be, and to protect the witness from undue harassment or embarrassment.

(b) With a witness under the age of 14 or a dependent person with a substantial cognitive impairment, the court shall take special care to protect him or her from undue harassment or embarrassment, and to restrict the unnecessary repetition of questions.  The court shall also take special care to ensure that questions are stated in a form which is appropriate to the age or cognitive level of the witness.  The court may, in the interests of justice, on objection by a party, forbid the asking of a question which is in a form that is not reasonably likely to be understood by a person of the age or cognitive level of the witness.