In Gordon v. Superior Court (1984) 161 Cal. App. 3d 157, the defendant admitted in interrogatories that its employee, Hayes, was acting in the course and scope of her employment when she was involved in an automotive collision with the plaintiff. ( Id. at p. 160.) The plaintiff moved to "establish that it was without substantial controversy that Hayes was acting within the course and scope of her employment at the time of the accident." ( Id. at p. 163.) The defendant opposed the motion and moved to amend its discovery responses, offering evidence that the initial discovery responses had been given in error. ( Id. at p. 164.) The Court of Appeal granted the plaintiff's petition for writ of mandate, holding the trial court erred in permitting the defendant to amend its interrogatory responses because the plaintiff had relied on the initial responses and so suffered prejudice. ( Id. at p. 168.)