A party moving to compel arbitration need not authenticate the opposing party’s signature on the agreement containing the arbitration clause in its initial moving papers but can wait until after the opposing party has challenged the authenticity of his signature.  So the trial court erred in excluding as untimely defendant’s supplemental declaration which was submitted after its moving papers but before plaintiff’s opposition.  Furthermore, by describing the security measures defendant took to assure that only plaintiff could sign his on-line employment agreement, which contained the arbitration clause, the supplemental declaration met defendant’s burden so the motion should be granted unless the trial court, on remand, finds the arbitration clause unconscionable, an issue it did not reach in its initial ruling.

California Court of Appeal., Second District, Division 4 (Collins, J.); April 22, 2016; 2016 WL 1613487