Cal. Evidence Code § 1416 : California Evidence Code — Writings — Authentication And Proof Of Writings — Means Of Authenticating And Proving Writings — Opinion testimony on handwriting Date: 31 Aug 2016 TEXT PDF Current through the 2016 Legislative Session A witness who is not otherwise qualified to testify as an expert may state his opinion whether a writing is in the handwriting of a supposed writer if the court finds that he has personal knowledge of the handwriting of the supposed writer. Such personal knowlegde may be acquired from: (a) Having seen the supposed writer write; (b) Having seen a writing purporting to be in the handwriting of the supposed writer and upon which the supposed writer has acted or been charged; (c) Having received letters in the due course of mail purporting to be from the supposed writer in response to letters duly addressed and mailed by him to the supposed writer; or (d) Any other means of obtaining personal knowledge of the handwriting of the supposed writer. Ca. Evid. Code § 1416