Barrister and Solicitor
Legal Writing and Research
Estoppel - Issue Estoppel
R. v. Dieckmann (Ont CA, 2017)
In this criminal case the Court of Appeal sets out the basics for the doctrine of issue estoppel, and clarifies that it can operate not only with respect to fact-findings made in prior proceedings, but with respect to prior consent judgments:
 The trial judge described the applicable test for issue estoppel:
1) the same question was decided in the prior proceeding;
2) the judicial decision said to create the estoppel is final; and
3) the parties to the prior decision are the same persons as the parties to the proceedings in which the estoppel is raised.
She noted that if the preconditions were established, a court still had to determine whether, as a matter of discretion, issue estoppel ought to be applied.
 The trial judge dismissed the application on the basis that the consent judgment was not a decision on the merits and it was unclear that the issues in the two proceedings were the same.
 Ms. Dieckmann argues that the trial judge erred in finding that the test for issue estoppel was not met.
 Contrary to the trial judge’s conclusion, a consent judgment may be the basis for issue estoppel: Hardy Lumber Co. v. Pickerel River Improvement Co. (1898), 1898 CanLII 16 (SCC), 29 S.C.R. 211; and Re Ontario Sugar Co. (1911), 24 O.L.R. 332 (C.A.), leave to appeal to S.C.C. refused (1911), 1911 CanLII 8 (SCC), 44 S.C.R. 659.