The principle of functus officio is based upon the finality of judgments and jurisdiction that once a formal decision is rendered, signed and communicated to the parties it cannot be re-opened. The Supreme Court of Canada’s decision in Chandler v. Alberta Association of Architects,  2 S.C.R. 848, is the leading case on functus officio. There, Justice Sopinka wrote that:
As a general rule, once such a tribunal has reached a final decision in respect to the matter that is before it in accordance with its enabling statute, that decision cannot be revisited because the tribunal has changed its mind, made an error within jurisdiction or because there has been a change of circumstances. It can only do so if authorized by statute or if there has been a slip or error within the exceptions enunciated in Paper Machinery Ltd. v. J. O. Ross Engineering Corp., supra.
To this extent, the principle of functus officio applies. It is based, however, on the policy ground which favours finality of proceedings
rather than the rule which was developed with respect to formal judgments of a court whose decision was subject to a full appeal. For this reason I am of the opinion that its application must be more flexible and less formalistic in respect to the decisions of administrative tribunals which are subject to appeal only on a point of law. Justice may require the reopening of administrative proceedings in order to provide relief which would otherwise be available on appeal.
In Jacobs Catalytic Ltd. v. International Brotherhood of Electric Workers, Local 353, 2009 ONCA 749 the Ontario Court of Appeal affirmed that a tribunal retaining jurisdiction over an aspect of a case is generally acceptable only where that aspect has not been fully addressed, and that a tribunal cannot arbitrarily reserve for itself extended jurisdiction over a completed aspect of a case.
Although the Federal Court Court has determined that functus officio does not apply so strictly as to preclude officers from re-visiting an application during an
applicant’s reconsideration request, from re-visiting applications when new information that was not previously disclosed to immigration authorities becomes available, and nor to prevent officers from re-evaluating an individual’s eligibility or admissibility during the processing of an application, it has consistently held that once a decision has been communicated to an individual and that individual receives a visa or permit then the decision cannot be revisited absent new information.
In Narvaez v. Canada (Citizenship and Immigration), for example, the Federal Court determined that functus officio prevented immigration authorities from revisiting final decisions even where the decisions were made in error. There, the Refugee Protection Division found that certain individuals were persons in need of protection, a decision which the Federal Court quashed on February 21, 2008. On April 4, 2008, a Citizenship and Immigration Canada officer reviewed the family’s application for permanent residency as people in need of protection, and issued them confirmations of permanent residence. On August 26, 2008, immigration authorities contacted the family to let them know that their permanent resident statuses were not valid, a decision which the family successfully challenged in Federal Court. Justice Frenette found that Citizenship and Immigration Canada could not nullify the family’s permanent residency, noting that:
I agree with the applicants’ argument that even if the officer’s decision to issue the applicants permanent residence was in retrospect made in error, this is not a basis for administratively re-opening the decision. A decision made in this case, even if wrongly made, is still a binding decision. While there may be some legal avenues to overturn a wrongly made decision, in the absence of statutory authority a decision once made cannot be administratively revisited simply because it may contain some error (see Chandler, above).
In Divinagracia v. Canada (Minister of Citizenship and Immigration), IMM-1098-98, the Federal Court ruled that functus officio prevented immigration authorities from revisiting a decision not to pursue misrepresentation allegations when the authorities had previously determined that they would not do so. There, immigration officials discovered that an applicant had committed misrepresentation by stating that she was single when she was in fact married. While an inadmissibility report was issued under s. 27 of the Immigration Act, immigration officials instead advised the individual that it was undertaking not to act “at this time” unless the applicant had committed another violation or did so in the future. However, upon discovering that the applicant’s spouse was medically inadmissible to Canada, immigration officials prepared a second report outlining the misrepresentation that had occurred and sought her deportation. The Federal Court found that given that there was no new violation by the applicant, the principle of functus officio prevented the misrepresentation allegation from being revisited, and quashed the referral decision.
Finally, in Canada (Public Safety and Emergency Preparedness) v. Siyaad, the Federal Court held that a decision of the Immigration Division to not release an individual’s passport is a final decision, and is functus.