What is the test for equalization in s. 15 of the Charter of Canada?

The courts have recognized that in the proper interpretation to be given to s. 15 of the Charter it must be recognized that most legislation draws distinctions with the result that it does not apply equally to all citizens. In dealing with the equality provisions of the Bill of Rights, McIntyre J., speaking for the majority, in MacKay v. R., 1980 CanLII 217 (SCC), [1980] 2 S.C.R. 370, [1980] 5 W.W.R. 385. 54 C.C.C. (2d) 129, 114 D.L.R. (3d) 393. 33 N.R. 1, said at p. 407 (S.C.R.): There are many such cases where the needs of society and the welfare of its members dictate inequality for the achievement of socially desirable purposes. It would be difficult, if not impossible, to propound an all-embracing test to determine what departures from the general principle of the equal application of law would be acceptable to meet a desirable social purpose without offence to the Canadian Bill of Rights. I would be of the opinion, however, that as a minimum it would be necessary to inquire whether any inequality has been created for a valid federal constitutional objective, whether it has been created rationally in the sense that it is not arbitrary or capricious and not based upon any ulterior motive or motives offensive to the provisions of the Canadian Bill of Rights, and whether it is a necessary departure from the general principle of universal application of the law for the attainment of some necessary and desirable social objective. Inequalities created for such purposes may well be acceptable under the Canadian Bill of Rights.