Cal. R. 4.116
This rule applies to all cases not filed in juvenile court in which the person charged by an accusatory pleading appears to be under the age of 18, except when jurisdiction over the child has been transferred from the juvenile court under Welfare and Institutions Code section 707.
(Subd (a) amended effective May 22, 2017; adopted effective January 1, 2001; previously amended effective January 1, 2007.)
If an accusatory pleading is pending, and it is suggested or it appears to the court that the person charged was under the age of 18 on the date the offense is alleged to have been committed, the court must immediately suspend proceedings and conduct a hearing to determine the true age of the person charged. The burden of proof of establishing the age of the accused person is on the moving party. If, after examination, the court is satisfied by a preponderance of the evidence that the person was under the age of 18 on the date the alleged offense was committed, the court must immediately certify the matter to the juvenile court and state on the certification order:
If the court determines that certification to the juvenile court is appropriate under (b), copies of the certification, the accusatory pleading, and any police reports must immediately be transmitted to the clerk of the juvenile court. On receipt of the documents, the clerk of the juvenile court must immediately notify the probation officer, who must immediately investigate the matter to determine whether to commence proceedings in juvenile court.
If the person is under the age of 18 and is in custody, the person must immediately be transported to the juvenile detention facility.
Cal. R. Ct. 4.116