In Jefferson Ins. Co. v. Superior Court (1970) 3 Cal.3d 398, the appraisers "determined as a matter of law that the issue before them was the 'replacement cost less depreciation' of the building, and that in arriving at the value listed in their award as 'cash value,' they refused to consider income, location, or any other relevant factor tending to show the fair market value of the property, despite the fact that such evidence was made available for their use." (Id. at pp. 401-402.) The trial court vacated the appraisal award pursuant to section 1286.2, determining "(1) that the appraisers had exceeded their powers by erroneously deciding a question of law (the meaning of 'actual cash value'), which they had not been authorized to decide, and (2) that the insured had been substantially prejudiced by the refusal of the appraisers to consider material evidence." (Jefferson, at p. 402.) The California Supreme Court concluded the trial court properly vacated the award because the "appraisers misinterpreted the meaning of 'actual cash value' and therefore failed to decide the factual issue submitted to them. . . ." (Jefferson, supra, 3 Cal.3d at p. 403.) The court explained, "where an appraisal award is based upon a misconception of the law, this fact may be proved to the court by extrinsic evidence, including a declaration of one of the appraisers. The declaration of an appraiser is properly received to show what the appraisers considered the issue to be, for the purpose of determining whether they exceeded their powers by making an error of law." (Ibid.)