What is the law around directed verdicts?

The starting point regarding the law discussing directed verdicts is United States of America v. Shephard 1976 CanLII 8 (SCC), [1977] 2 S.C.R 1067 wherein Justice Ritchie indicated: I agree that the duty imposed upon a "justice" under s. 475(1) is the same as that which governs a trial judge sitting with a jury in deciding whether the evidence is "sufficient" to justify him in withdrawing the case from the jury and this is to be determined according to whether or not there is any evidence upon which a reasonable jury properly instructed could return a verdict of guilty. The "justice", in accordance with this principle, is, in my opinion, required to commit an accused person for trial in any case in which there is admissible evidence which could, if it were believed, result in a conviction.