California Code, Vehicle Code - VEH § 17701

No application for a driver's license shall be granted by the department to any minor unless it is signed and verified by the father and mother of such minor, if both father and mother are living and have custody of the minor.

If only one parent is living or has custody, the application shall be signed and verified by that parent.

If neither parent is living or has custody, the application shall be signed and verified by the guardian, or if there is no guardian, by a person having custody of the minor.

If the minor is a dependent or ward of the court, the application may be signed by a grandparent, sibling over the age of 18 years, aunt, uncle, or foster parent with whom the minor resides.  The probation officer or child protective services worker acting as an officer of the court, on behalf of a child, may also sign and verify the application of a minor who is a dependent or ward of the court, if the minor files proof of financial responsibility as provided in Article 1 (commencing with Section 16430) of Chapter 3 of Division 7 at the time of application.  Prior to signing the application, the probation officer or child protective services worker shall notify the foster parents or other responsible party of his or her intent to sign and verify the application.