California Code, Labor Code - LAB § 5814.1

When the payment of compensation has been unreasonably delayed or refused prior to the issuance of an award, and the director has provided discretionary compensation pursuant to Section 4903.3, the appeals board shall award to the director a penalty to be paid by the employer in the amount of 10 percent of the compensation so provided by the director, such penalty to be in addition to the penalty imposed by Section 5814.  The question of delay and the reasonableness of the cause therefor shall be determined by the appeals board in accordance with the facts.