California Code, Elections Code - ELEC § 14224

(b)(1) Except as provided in paragraph (2), a voter shall not remain in or occupy a voting booth or compartment longer than is necessary to mark his or her ballot, which shall not exceed 10 minutes.

(2) If a voter informs a precinct board member that the voter requires additional time to mark his or her ballot, a longer period shall be allowed.  However, if the precinct board member determines that the voter is attempting to interfere with the conduct of the election and does not require additional time to mark his or her ballot, the precinct board member may contact the elections official, who may order that the voter not be provided with additional time to mark his or her ballot.