Pèse Pêche Inc. v. R, 2013 NBCA 37 holds:
At the outset, it bears noting that the decision whether to grant or refuse a prerogative remedy such as certiorari is ultimately a matter of discretion, exercised by the superior court as part of its general and inherent jurisdiction. Moreover, the scope of review by certiorari is very limited, being conducted "only where it is alleged that [a lower court] has acted in excess of its assigned statutory jurisdiction or has acted in breach of the principles of natural justice which, by the authorities, is taken to be an excess of jurisdiction" (Gallant, LeBlanc and Steeves v. R., 2009 NBCA 84 (CanLII), 2009 NBCA 84, 352 N.B.R. (2d) 333, at para. 7). See, on point, Harelkin v. University of Regina, 1979 CanLII 18 (SCC),  2 S.C.R. 561, at para. 29; the comments of Richard J.A., writing for the Court in Gallant, LeBlanc and Steeves v. R., at paras. 7-9; and those of Robertson J.A. in Chapelstone Developments Inc., Action Motors Ltd. and Hamilton v. Her Majesty the Queen in Right of Canada, 2004 NBCA 96 (CanLII), 2004 NBCA 96, 277 N.B.R. (2d) 350, at paras. 11-19.
Finally, the nature of this power is such that "[e]ven when jurisdictional error is found, certiorari is a discretionary remedy that may be refused" (see Gallant, LeBlanc and Steeves v. R., at para. 13).
The standard of review applicable to appeals from discretionary orders is set out in The Beaverbrook Art Gallery v. Beaverbrook Canadian Foundation, 2013 NBCA 17 (CanLII), 2013 NBCA 17,  N.B.J. No. 51 (QL) (per Drapeau, C.J.N.B.):
[…] The impugned Order is quintessentially the product of an exercise of judicial discretion. Like any other discretionary judicial decision, it may be interfered with on appeal only if it is founded upon an error of law, an error in the application of the governing principles or a palpable and overriding error in the assessment of the evidence (see British Columbia (Minister of Forests) v. Okanagan Indian Band, 2003 SCC 71 (CanLII),  3 S.C.R. 371, 2003 SCC 71 at par. 43) or if it is unreasonable, in the sense that nothing in the record can justify it (see The Honourable R.P. Kerans, Standards of Review Employed by Appellate Courts (Edmonton: Juriliber Limited, 1994), at pp. 36-37 and Secretary of State for Education and Science v. Tameside Metropolitan Borough Council,  A.C. 1014 (H.L.) Lord Diplock at p. 1064). [para. 8]
Applying this standard and having regard to the fact that the judge refused to examine the applications on the merits, it is apparent we must decide whether the decision of the application judge is unreasonable by reason that nothing in the record can justify it.