What is the test for equality under section 15(1) of the Charter of Canada?

The starting point for the analysis of section 15(1) is Andrews v. Law Society of B.C. (1989), 1989 CanLII 2 (SCC), 56 D.L.R. (4th) 1 (S.C.C.), where McIntyre J. stated at p. 10: The concept of equality has long been a feature of Western thought. As embodied in section 15(1) of the Charter, it is an elusive concept and, more than any of the other rights and freedoms guaranteed in the Charter, it lacks precise definition....It is a comparative concept, the condition of which may only be attained or discerned by comparison with the condition of others in the social and political setting in which the question arises. It must be recognized at once, however, that every difference in treatment between individuals under the law will not necessarily result in inequality and, as well, that identical treatment may frequently produce serious inequality.