Does a plaintiff have to prove that he and his attorney knew the identity of the substituted defendant long before he filed a claim?

^7. The cases cited by defendants are inapposite. For example, in Stephens v. Berry (1967) 249 Cal.App.2d 474, the plaintiff was not in fact ignorant of the defendant's identity, because he and the defendant had exchanged each other's names, license numbers and driver's license information after the car accident at issue; the defendant gave the plaintiff his insurance carrier and policy number; and the plaintiff's attorney wrote to the defendant's insurance company before filing the complaint, which named the wrong person as the party who rear-ended the plaintiff. (Id. at pp. 475-476.) Thus, the evidence showed the plaintiff and his attorney knew the substituted defendant's identity and his liability "long before suit was filed." (Id. at p. 477.)