Opinion as to handwriting and signature: Certifying Authority opinion on electronic signatures is relevant to court. When the court determines who wrote or signed a document, the opinion of any person acquainted with the alleged author's handwriting is relevant; 'acquainted' includes having seen the person write, exchanged documents with them, or habitually receiving documents purportedly in their hand in the ordinary course of business. When forming an opinion about an electronic signature, the opinion of the Certifying Authority that issued the Electronic Signature Certificate is relevant.