California Code, Code of Civil Procedure - CCP § 226

(a) A challenge to an individual juror may only be made before the jury is sworn.

(b) A challenge to an individual juror may be taken orally or may be made in writing, but no reason need be given for a peremptory challenge, and the court shall exclude any juror challenged peremptorily.

(c) All challenges for cause shall be exercised before any peremptory challenges may be exercised.

(d) All challenges to an individual juror, except a peremptory challenge, shall be taken, first by the defendants, and then by the people or plaintiffs.