Issue estoppel applies only where a Court's decision necessarily determines the issue

R. v. Thompson, 2014 ONCA 43:

[33]       The doctrine of issue estoppel is concerned with particular issues common to two different pieces of litigation involving the same parties:  R. v. Mahalingan, 2008 SCC 63, [2008] 3 S.C.R. 316, at para. 17.  When applied to a trial, the doctrine focuses on particular determinations of the issues supporting the verdict, not on the ultimate verdict itself, which is the business of double jeopardy:  Mahalingan, at para. 17.

[34]       Where the doctrine of issue estoppel applies, it prevents the Crown from re-litigating an issue that has been decided in the accused's favour with finality in a prior criminal proceeding:  Mahalingan, at para. 31.

[35]       The first requirement for a claim of issue estoppel is that an issue has been decided in a prior proceeding:  Mahalingan, at paras. 49 and 52.  The onus of proving this threshold requirement falls upon the accused who seeks to invoke the doctrine:  Mahalingan, at para. 52. 

[36]       To satisfy this onus, an accused must show that the question was or must necessarily have been resolved on the merits in the accused's favour in the earlier proceeding:  Mahalingan, at para. 52.  It is not enough to show that the evidence was adduced in an earlier proceeding and an acquittal entered: Mahalingan, at para. 52.  It must be a necessary inference, either from the judge's findings or from the fact of the result, that the issue was resolved in the accused's favour:  Mahalingan, at para. 52.