Cal. Sts. & High. Code § 5223

If it shall be necessary, in order to find whether a majority protest exists, to determine whether any or all of the signers of written protests are the “owners” of property to be assessed, the legislative body shall make such determination from the last equalized assessment roll, any written evidence submitted with a written protest and any other evidence received at the hearing. The legislative body shall be under no duty to obtain or consider any other evidence as to ownership of property and its determination of ownership shall be final and conclusive.