California Code, Public Utilities Code - PUC § 785.5

(a) The commission shall require every gas corporation to adopt and pursue purchasing and procurement practices which assure its customers the lowest rates consistent with security of supply and with Section 785.

(b) Pursuant to subdivision (a), the commission may establish and periodically revise for each gas corporation guidelines for priorities among suppliers and sources of supply of gas to gas corporations, taking into consideration the requirements of Section 785.  The establishment of these guidelines does not relieve a gas corporation of any requirement to make reasonable and prudent purchases of gas or diminish the authority of the commission to review the reasonableness of any purchase or procurement decision of the corporation.