Intervention in Charter cases

R. v. Mernagh, 2012 ONCA 199:

[15]       Where the intervention is in the context of a Charter case, whether an intervener has an important perspective distinct from the immediate parties is an important factor to consider on such applications: Ontario (Attorney General) v. Dieleman (1993), 16 O.R. (3d) 32. Whether or not the applicants' positions ultimately prevail, they will still provide a unique viewpoint that will not otherwise be made and which may be useful to the court.

[16]       As Chief Justice Dubin stated in Peel (Regional Municipality) v. Great Atlantic & Pacific Co. of Canada (1990), 74 O.R. (2d) 164, at p. 167:

Although much has been written as to the proper matters to be considered in determining whether an application for intervention should be granted, in the end, in my opinion, the matters to be considered are the nature of the case, the issues which arise and the likelihood of the applicant being able to make a useful contribution to the resolution of the appeal without causing injustice to the immediate parties.