Courts - Functus Officio'Functus officio' is a doctrine which draws the line between when a court or tribunal loses the ability to rule in a matter by virtue of exhausting it's jurisdiction, and when any other legal activity is restricted to appeals or judicial review. It commonly arises in issues of 're-opening', which are addressed here in the Civil Appeals section as they offer an 'appeal-like' remedy in some circumstances: Appeals from the Superior Court: Re-openings.
. R. v. Khan
In R. v. Khan (Ont CA, 2022) the Court of Appeal considered functus officio and the re-opening of a case in a criminal context:
 In a judge-alone criminal trial, trial judges are not functus officio until after they have imposed a sentence or otherwise made a final disposition in the matter: see R. v. Sualim, 2017 ONCA 178, 135 O.R. (3d) 81, at para. 29, referring to R. v. Lessard (1976), 1976 CanLII 1417 (ON CA), 30 C.C.C. (2d) 70 (Ont. C.A.), at p. 73, and R. v. Griffith, 2013 ONCA 510, 116 O.R. (3d) 561, at para. 12.
 Accordingly, as stated in R. v. Kraftchick (1991), 44 O.A.C. 313 (C.A.), at p. 315, the appropriate time to seek to reopen a trial is during the sentencing hearing:
The trier of fact in this case was the trial judge and he was still seized of the case at the sentencing hearing. The sentencing hearing was the appropriate time to ask the trial judge to re-open the conviction issue and, if it was thought necessary, to direct a mistrial. No such application was made by the defence. Furthermore, where an application to reopen rests on the admission of additional evidence, the applicant must meet the criteria for fresh evidence in R. v. Palmer, 1979 CanLII 8 (SCC),  1 S.C.R. 759: see R. v. N.G., 2020 ONCA 494, 152 O.R. (3d) 24, at para. 43.