California Code, Code of Civil Procedure - CCP § 1299.6

(a) The arbitration panel shall direct that five days prior to the commencement of its hearings, each of the parties shall submit the last best offer of settlement as to each of the issues within the scope of arbitration, as defined in this title, made in bargaining as a proposal or counterproposal and not previously agreed to by the parties prior to any arbitration request made pursuant to subdivision (a) of Section 1299.4. The arbitration panel, within 30 days after the conclusion of the hearing, or any additional period to which the parties agree, shall separately decide on each of the disputed issues submitted by selecting, without modification, the last best offer that most nearly complies with the applicable factors described in subdivision (c). This subdivision shall be applicable except as otherwise provided in subdivision (b).

(b) Notwithstanding the terms of subdivision (a), the parties by mutual agreement may elect to submit as a package the last best offer of settlement made in bargaining as a proposal or counterproposal on those issues within the scope of arbitration, as defined in this title, not previously agreed to by the parties prior to any arbitration request made pursuant to subdivision (a) of Section 1299.4. The arbitration panel, within 30 days after the conclusion of the hearing, or any additional period to which the parties agree, shall decide on the disputed issues submitted by selecting, without modification, the last best offer package that most nearly complies with the applicable factors described in subdivision (c).

(c) The arbitration panel, unless otherwise agreed to by the parties, shall limit its findings to issues within the scope of arbitration and shall base its findings, opinions, and decisions upon those factors traditionally taken into consideration in the determination of those matters within the scope of arbitration, including but not limited to the following factors, as applicable: