A routine application of issue estoppel, applying R v Mahalingan [2008] SCC 63 (noted here on 15 November 2008) is R v Punko, 2012 SCC 39. In a multi-issue trial it could not be said that there was the necessary logical connection between the verdict and the issue now before the court, so there was no estoppel.
More interesting is the only point that divided the Court: Fish J disagreed with the majority judgment delivered by Deschamps J on whether a judge's finding of fact at sentencing could in principle give rise to issue estoppel. The majority held that it could not, because it was not a decision on the merits, that is, relevant to verdict, and issue estoppel requires a logically necessary conclusion that the jury were unanimous on the issue [11]-[12]. At sentencing the judge makes findings of fact to elucidate the jury's verdict of guilty, but in relation to counts on which the jury acquitted the defendant the judge in sentencing on the guilty verdicts has no power to make a finding binding on future judges [12].
Fish J, who agreed with everything else, considered that the sentencing powers of a judge included the power to find any relevant fact that was disclosed by the evidence, and that the question whether a fact found at sentencing could give rise to issue estoppel should be left open as a matter of principle [26]-[27].
One would have thought that if a sentencing judge finds a particular fact to have been proved beyond reasonable doubt, the issue is settled and the estoppel should apply.
Punko illustrates the narrowness of issue estoppel. Deschamps J did comment on how the doctrine of abuse of process could come into play if the prosecution's conduct were to be found to be "sufficiently egregious" [21]. In commenting on Mahalingan I noted that abuse of process can be of more use than issue estoppel in criminal law, if only the courts will get to grips with giving it meaning instead of dismissing it as something too vague.
