Does Respondent evidence fail to qualify as responsive?

Evidence does not fail to qualify as “responsive” simply because the need for calling it was or could have been anticipated in advance: see Tsoukas v. Segura, supra, (per Finch C.J.B.C.) at ¶37). Indeed, in that case the defendants had pleaded the particular position that the proposed defence expert evidence supported, and it should therefore have been clear to the plaintiff that her own position would be challenged; the trial judge’s decision to admit the oral evidence, though not the written report, could not be said to have surprised the plaintiff, or to have occasioned an unfair trial.

But I conclude that the present situation is closer to that in Stewart v. Chen, where Joyce J. concluded that the proposed defence evidence was not truly responsive to a matter raised by the expert evidence tendered by the plaintiff. That was in part because the proposed evidence would have addressed a matter that had already been addressed by another of the defence’s expert witnesses. The evidence thus “would have permitted [the defence] to expand their case, without notice …” (¶17). Joyce J. observed that to admit, without notice, further defence expert evidence as to that subject would in the circumstances have been to have permitted “trial by ambush”.