Is a finding of fact unreasonable and constitutes jurisdictional error?

48 A finding of fact is unreasonable and constitutes jurisdictional error if there is no evidence before the tribunal to justify its finding, or if, in light of that evidence, its finding appears to be wholly unreasonable. In such a case, the error of fact is described as an error of law which deprives the tribunal of jurisdiction: Blanshard v. Control Data Limited, 1984 CanLII 27 (SCC), [1984] 2 S.C.R. 476 at 494-495. If, on the other hand, there is some evidence before the tribunal which permitted it to rationally reach its conclusion, there is no jurisdictional error. As Lamer J. (as he then was) stated in Blanshard: An administrative tribunal has the necessary jurisdiction to make a mistake, even a serious one, but not to be unreasonable.