California Code, Labor Code - LAB § 6627

Any person affected by an order or decision of the appeals board may, within the time limit specified in this section, apply to the superior court of the county in which he resides, for a writ of mandate, for the purpose of inquiring into and determining the lawfulness of the original order or decision or of the order or decision following reconsideration.  The application for writ of mandate must be made within 30 days after a petition for reconsideration is denied, or, if a petition is granted or reconsideration is had on the appeals board's own motion, within 30 days after the filing of the order or decision following reconsideration.