California Code, Revenue and Taxation Code - RTC § 1610.8

After giving notice as prescribed by its rules, the county board shall equalize the assessment of property on the local roll by determining the full value of an individual property, by assessing any taxable property that has escaped assessment, correcting the amount, number, quantity, or description of property on the local roll, canceling improper assessments, and by reducing or increasing an individual assessment, as provided in this section. The full value of an individual property shall be determined without limitation by reason of the applicant's opinion of value stated in the application for reduction in assessment pursuant to subdivision (a) of Section 1603.

The applicant for a reduction in an assessment on the local roll shall establish the full value of the property by independent evidence. The records of the assessor may be used as part of such evidence.

The county board shall make a determination of the full value of each parcel for which an application for equalization is made.