More on Mandamus -- from Justice Boivin's decision (http://decisions.fct-cf.gc.ca/en/2010/2010fc767/2010fc767.html):
 Mandamus is a discretionary equitable remedy. It lies to compel the performance of a public legal duty which a public authority refuses or neglects to perform although duly called upon to do so. In Kalachnikov v. Canada (Minister of Citizenship and Immigration), 2003 FCT 777,  F.C.J. No. 1016, from paragraphs 11 to 13, Justice Snider reviewed the requirements for mandamus in the immigration context:
The Test for Mandamus
 Mandamus is a discretionary, equitable remedy (Khalil v. Canada (Secretary of State),  4 F.C. 661 (C.A.)) subject to the following conditions precedent.
1. There is a public duty to the applicant to act;
2. The duty must be owed to the applicant;
3. There is a clear right to performance of that duty, in particular:
(a) the applicant has satisfied all conditions precedent giving rise to the duty;
(b) there was a prior demand for performance of the duty, a reasonable time to comply with the demand, and a subsequent refusal which can be either expressed or implied, e.g. unreasonable delay; and
4. There is no other adequate remedy.
5. The "balance of convenience" favours the applicant (Apotex Inc. v. Canada (A.G.),  1 F.C. 742 (C.A.), aff'd  3 S.C.R. 1100, Conille v. Canada (Minister of Citizenship and Immigration),  2 F.C. 33 (T.D.)).
 In Conille, supra,  2 F.C. 33 (T.D.), Tremblay-Lamer J. set out three requirements at paragraph 23, that must be met if a delay is to be considered unreasonable:
(1) The delay in question has been longer than the nature of the process required, prima facie;
(2) The applicant and his counsel are not responsible for the delay; and
(3) The authority responsible for the delay has not provided satisfactory justification.
 In Mohamed v. Canada (Minister of Citizenship and Immigration),  F.C.J. No. 1677 (T.D.) (QL), Dawson J. cautioned at paragraph 15 that prior jurisprudence is "not particularly helpful except for the purpose of outlining the parameters within which the Court has issued an order in the nature of mandamus where it has found an unusual delay which has not been reasonably explained." Dawson J. granted the order for mandamus in Mohamed, supra because of the length of the delay in completing the security review and the lack of explanation for why the estimated six months to one year processing time was exceeded. Dawson J. did not accept that the statement that the delays had to do with security concerns was a satisfactory justification for the fact that, after more than four years, the applicant's application for landing was still outstanding.