California Code, Government Code - GOV § 62576

(a) In any judicial action or proceeding to validate, attack, review, set aside, void, or annul any resolution providing for the establishment, increase, or imposition of a commercial linkage fee pursuant to this article in which there is an issue whether the fee is a special tax within the meaning of Section 50076, the authority shall have the burden of producing evidence to establish that the commercial linkage fee does not exceed the reasonable cost of providing the housing necessitated by the commercial development project for which the commercial linkage fee is imposed, as determined in the regional nexus study pursuant to subdivision (b) of Section 62571.

(b) A party may only initiate an action or proceeding pursuant to subdivision (a) if both of the following requirements are met:

(c) For purposes of this section, costs shall be determined in accordance with fundamental fairness and consistency of method as to the allocation of costs, expenses, revenues, and other items included in the calculation.