Reopening the Case
Once a party has closed their case, it is presumed they have finished presenting their evidence. It is the judge's discretion to allow a party, usually the Crown, to re-open their case.
The factors to consider in exercising discretion to re-open a case prior to verdict are:
- whether the evidence is relevant to a material issue in the case;
- the potential prejudice to the other party, if reopening is permitted; and
- the effect of permitting reopening on the orderly and expeditious conduct of the trial.
The main consideration is the potential prejudice to the opposing side by re-opening the case.
Re-opening the Defence's Case
The test to re-open the defence's case is more stringent post-conviction in order "to protect the integrity of the process, including the enhanced interest in finality". In such cases, the test will be the same for admitting fresh evidence on appeal.
The test to re-open the defence's case after adjudication requires the applicant to establish:
- the evidence should generally not be admitted if, by due diligence, it could have been adduced at trial. This general principle will not be applied as strictly in criminal trials as in civil trials;
- the evidence must be relevant in the sense that it bears upon a decisive or potentially decisive issue at trial;
- the evidence must be credible in the sense that it is reasonably capable of belief; and
- it must be such that if believed it could reasonably be expected, when taken with the other evidence adduced at trial, to have affected the result.
The judge should consider whether the application is an attempt to reverse a tactical decision at trial.
Re-opening the Crown's Case
The judge may consider an application by the Crown to reopen their case. The standard will depend on what stage in the trial the application is made.
The decision to re-open the case is a discretionary one and will be accorded deference on review.
The central issue is whether re-opening the case will cause prejudice to the accused.
A failure to request that the voir dire evidence be admitted into the trial by omission can be reason to reopen the crown case.
The further along the trial is the narrower the discretion and the more likely the prejudice will prevent reopening.
The analysis will depend on what phase of trial the application is brought. The first phase is before the closing of the Crown case. The second phase is after closing of Crown case but before defence elects to call evidence. The third and final phase is once the defence has started calling evidence.
- After Defence Begins Evidence (The "Third Phase")
The judge has the discretion to reopen the case "to correct some oversight or to prove a matter which it had failed to do inadvertently, provided that there was no prejudice to the accused." However, "[o]nce the defence had begun to present its case, the judge’s discretion [is] narrowly restricted" and may only be reopened "to prove a matter, ex improviso, which no human ingenuity could have foreseen." 
R v Robillard, 1978 CanLII 200 (SCC), per Pigeon J
R v P(MB), 1994 CanLII 125 (SCC),  1 SCR 555, per Lamer CJ
R v G(SG), 1997 CanLII 311 (SCC),  2 SCR 716, per Cory J (plurality)
See also R. E. Salhany, Q.C., Canadian Criminal Procedure, 6th ed., looseleaf (Aurora: Thomson Reuters Canada Limited, 2010) vol. 1 at paras 6.3975, 6.3980, 6.3990
- G(SG), supra, at para 29
- G(SG), supra, at para 29 (The "crucial question to be resolved upon an application to reopen the Crown’s case is whether the accused will suffer prejudice in the legal sense ‑‑ that is, will be prejudiced in his or her defence"(cleaned up))
- R v Wu, 2010 ABCA 337 (CanLII), per curiam
- G(SG), supra, at para 30 ("discretion to allow the Crown to reopen its case becomes narrower as the trial proceeds because of the increasing likelihood of prejudice to the accused’s defence as the trial progresses.")
- G(SG), supra, at para 30
P(MB), supra at 568–570 (SCR), (the Crown will “be permitted to correct some oversight or inadvertent omission … in the presentation of its case, provided that justice requires it and there will be no prejudice to the defence.”)
Re-Opening Post Verdict
The trial judge retains the discretion to reopen a trial after giving a trial verdict. The court is guided by the interest of "protecting the integrity of the process" and should only be done in the clearest of cases.
The exercise of discretion should "only to be exercised in exceptional circumstances, where its exercise is clearly called for".
Where the application is based on "fresh evidence" the applicant must satisfy the Palmer test for fresh evidence.
- Appellate Review
On a judge-alone trial, the trial judge should consider the Palmer factors for Fresh Evidence. The judge should not reopen the case where it is seen as "an attempt to reverse a tactical decision made at trial".
The decision to reopen a trial should not be overturned unless there was a "misdirection" or an "unreasonable exercise of discretion".
R v Arabia, 2008 ONCA 565 (CanLII), per Watt JA, at para 52
R v Hailemolokot, 2014 CanLII 56993 (MB CA), per Burnett JA, at paras 8, 10
R v Chan, 2019 ONSC 783 (CanLII), per Boswell J, at para 27 ("Where an application is brought to re-open a case following judgment, but before sentencing, the trial judge has a discretion to re-open the case and to reconsider the judgment.")
Chan, supra, at paras 27 to 28 - referring to it as the "Lessard" test
R v Lessard, 1976 CanLII 1417 (ON CA), 30 CCC (2d) 70, per Martin JA, at p. 73 (“should only be exercised in exceptional circumstances and where its exercise is clearly called for”)
R v Griffen, 2013 ONCA 510 (CanLII), , 116 OR (3d) 561, per Rosenberg JA, at para 12
R v Kowall, 1996 CanLII 411 (ON CA), 108 CCC (3d) 481, per curiam, at para 31
R v Drysdale, 2011 ONSC 5451 (CanLII), 275 CCC (3d) 219, per Trotter J, at para 1
Chan, supra, at para 28
See also Appellate Evidence#Fresh Evidence
Hailemolokot, ibid., at para 9
Hailemolokot, ibid., at para 9
Hailemolokot, ibid., at para 10