Is there a requirement that expert testimony about future earning capacity be presented before the jury is entitled to determine compensation for loss of earnings?

Contrary to defendant's claim, there is no requirement that expert testimony about future earning capacity be presented before the jury is entitled to determine compensation for loss of future earnings. Lang v. Barry (1945) 71 Cal.App.2d 121, 161 P.2d 949 is illustrative. At the time of the accident, the plaintiff was a 16-year-old part-time gas station attendant. (Id. [66 Cal.App.4th 1281] at p. 123, 161 P.2d 949.) He presented expert testimony from his physician about the nature and extent of his injuries. Evidence was also presented that the injury disqualified plaintiff from regular military service and that he "had been accepted only for limited service as a specialist." (Id. at p. 126, 161 P.2d 949.) The jury rendered a verdict in plaintiff's favor. On appeal, defendant contended that the court erred in instructing the jury that it could consider the permanence of plaintiff's injuries in determining damages. The appellate court rejected the contention. It first found plaintiff's evidence supported submitting to the jury the issue of the permanence of the injuries. Then, in language applicable to this case, it held: "The permanent weakness of the left leg having been shown, impairment of the minor plaintiff's earning power could properly be considered by the jury, being within the knowledge and observation of the jury as persons of ordinary intelligence and experience. [Citations.]" (Id. at pp. 126-127, 161 P.2d 949.)