California Code, Government Code - GOV § 15612

The board may inspect, either as a board, individually, or by its duly appointed representative, the work of any local officers whose duties relate to the assessment of property for taxation and the collection of taxes. It may require such officers to produce any records in their custody, including, but not limited to, records relating to the assessment of specific properties and give testimony with reference to such matters of assessment and tax collecting as it deems useful to it in its investigations.