Juries (Civil) - Discharging a Jury. St. Marthe v. O’Connor
In St. Marthe v. O’Connor (Ont CA, 2021) the Court of Appeal considered the discharging of a civil jury:
The Law on Discharging a Jury. Girao v. Cunningham
 The right to a jury trial is a substantive right: Cowles v. Balac (2006), 2006 CanLII 34916 (ON CA), 273 D.L.R. (4th) 596 (Ont. C.A.), at para. 36. After deciding that a particular reference before a jury is prejudicial, the trial judge must determine whether the prejudice is so severe that specific instructions cannot dispel that prejudice. The jury should only be discharged if the prejudice cannot be cured. In most cases, the trial judge will be able to fashion a remedy short of discharging the jury: Hamstra (Guardian ad litem of) v. British Columbia Rugby Union, 1997 CanLII 391 (SCC),  1 S.C.R. 1092, at paras. 17, 23.
 Discharging a jury is a “drastic remedy”: Brady v. Lamb (2005), 2005 CanLII 46734 (ON CA), 78 O.R. (3d) 680 (C.A.), at para. 13.
 However, a trial judge’s decision to discharge a jury is a discretionary decision that will not be interfered with on appeal unless it “was exercised arbitrarily or capriciously or was based upon a wrong or inapplicable principle of law”: Cowles v. Balac, at paras. 36-42, leave to appeal refused,  S.C.C.A. No. 496, citing Kostopoulos v. Jesshope (1985), 1985 CanLII 2047 (ON CA), 50 O.R. (2d) 54 (C.A.) at p. 69, leave to appeal refused,  S.C.C.A. No. 93.
The case of Girao v. Cunningham (Ont CA, 2020) is a remarkable ruling. That it had to be written this way is an embarrassment to the legal profession. It should be read by any litigation lawyer, especially those practicing MVA litigation, as a salutory lesson in dealing with self-representing parties. On it's face it was an appeal of an MVA tort jury award, but the Court of Appeal took the oppourtunity to review numerous (sadly, necessary) basics of civil litigation. Dealing at trial with a self-represented plaintiff who relied on a Spanish interpreter throughout, the Court of Appeal used defence behaviour as object lessons in why these legal principles are important and in the end, took the unusual step of ordering a new trial from scratch [paras 7, 173-174].
I'll go through the legal principles one by one as per topic, here striking the jury:
 The principles governing the discharge of a jury and appellate review were set out in Kempf v. Nguyen, 2015 ONCA 114, 124 O.R. (3d) 241, by Epstein J.A. for the majority, at para. 43, and by Laskin J.A. who dissented but not on this point, at para. 118. Both relied on Cowles v. Balac (2006), 2006 CanLII 34916 (ON CA), 83 O.R. (3d) 660, leave to appeal refused,  S.C.C.A. No. 496.
 The respondent relies on the premise underlying these decisions: “[T]he moving party has a substantial onus because trial by jury is a fundamental right”: McDonald-Wright v. O’Herlihy, 2007 ONCA 89, 220 O.A.C. 110, at para. 13, per Gillese J.A., who cited Hunt (Litigation Guardian of) v. Sutton Group Incentive Realty Inc. (2002), 2002 CanLII 45019 (ON CA), 60 O.R. (3d) 665 (C.A.). The respondent also relies on McDonald-Wright to support her position that the trial judge did not err in declining to strike the jury
 To paraphrase several principles invoked by Epstein J.A. in Kempf, at para. 43 (5) and (7): Complexity of a case is a proper consideration in determining whether a jury notice should be struck, and that relates not only to the facts and the evidence, but also to the legal principles that apply to the case. Trial judges are presumed to know the law and to be able to explain it to a jury.
 In Kempf, at para. 119, Laskin J.A. said: “The question for the trial judge is simply this: will justice to the parties be better served by dismissing or retaining the jury?” This standard has been cited in numerous cases: see e.g. Cowles, at para. 37; Graham v. Rourke (1990), 1990 CanLII 7005 (ON CA), 75 O.R. (2d) 622,  O.J. No. 2314, at para. 6. In Graham, Doherty J.A. continued at para. 6: “In many situations that discretion may, with equal propriety, be exercised for or against discharging the jury.”
 As Laskin J.A. further pointed out in Kempf, at para. 119, in assessing whether a trial judge exercised discretion appropriately about whether to retain or discharge a jury, “context matters. Although the right to a trial by jury in a civil case is an important right, it is far from absolute.”
 One contextual issue clearly at play with respect to Ms. Girao is the degree to which, if at all, a trial judge should consider a party’s self-represented status, among other factors, when determining whether to strike a jury. I addressed this issue in the immediately preceding section of these reasons.
 The cases in which the principles have been expressed have tended to be family law cases in which there is no jury. But there are cases in which a party’s self-represented status was a factor considered by the trial judge in determining whether to strike a jury notice. In Desjardins v. Arcadian Restaurants Ltd. (2005), 2005 CanLII 27388 (ON SC), 77 O.R. (3d) 27 (Ont. S.C.), the defendant filed a jury notice but then later brought a motion to strike the jury several months before trial. The self-represented plaintiff opposed the motion. The motion judge initially dismissed the motion to strike without prejudice to the defendant on the belief that “with proper instructions to the plaintiff and to the jury, [he] would be able to manage the trial in a manner that would be perceived by the jury to be fair to both sides”: at para. 12. However, he left it open to the defendant to renew the motion at trial. When the defendant renewed the motion closer to trial, the motion judge granted the motion to strike the jury notice, noting that the self-represented status of the plaintiff has made the case “unduly complicated” so that the trial would be prolonged as a result: at para. 11(i) and (ii). He explained: “I have now come to the conclusion that it will virtually be impossible to provide the assistance I anticipate the plaintiff will require at trial in a manner that ensures that the defendant will not be placed at a significant disadvantage in the eyes of the jury”: at para. 13. See also Belende c. Greenspoon, 2006 Carswell 9135.