California Code, Business and Professions Code - BPC § 16728

(a) Notwithstanding any other provision of law, motor carriers of property, as defined in Section 34601 of the Vehicle Code, may voluntarily elect to participate in uniform cargo liability rules, uniform bills of lading or receipts for property being transported, uniform cargo credit rules, joint line rates or routes, classifications, mileage guides, and pooling.  Motor carriers of property that so elect shall comply with all requirements of Section 14501(c) of Title 49 of the United States Code and with federal regulations promulgated pursuant to that section.  The Legislature intends by this section to provide to motor carriers of property the antitrust immunity authorized by state action pursuant to Section 14501(c) of Title 49 of the United States Code.

(b) The election authorized by this section shall be exercised in either of the following ways:

(c) The elections made by a motor carrier of property pursuant to this section may be canceled by the motor carrier.