Cal. Pub. Util. Code § 2107.5

When the commission finds, after hearing, that any person or corporation has knowingly aided or abetted a common carrier in violating Section 458 or has violated Section 459, or any order, decision, rule, regulation, direction, demand, or requirement issued under those provisions, the commission may impose a fine for each violation not to exceed five thousand dollars ($5,000). In addition to the fine, the commission may impose interest on the fine, not to exceed the maximum rate of interest provided for in Section 1 of Article XV of the Constitution. Interest shall commence to accrue on the date when the payment of the fine becomes delinquent.