Justice Abella wrote as follows (at paras. 5, 46-48, 50-63, 69-72, 81-82, 138):

"Full-time RCMP members who job‑share must sacrifice pension benefits because of a temporary reduction in working hours. This arrangement has a disproportionate impact on women and perpetuates their historical disadvantage. It is a clear violation of their right to equality under s. 15(1) of the Charter.

...

The Court most recently addressed this issue in Taypotat. While concluding that there was no discrimination demonstrated on the facts of the case, the Court acknowledged that “facially neutral qualifications like education requirements” can be a breach of s. 15(1) because of their “disproportionate effect” on protected groups (paras. 15 and 22).

There is no doubt, therefore, that adverse impact discrimination “violate[s] the norm of substantive equality” which underpins this Court’s equality jurisprudence (Withler, at para. 2). At the heart of substantive equality is the recognition that identical or facially neutral treatment may “frequently produce serious inequality” (Andrews, at p. 164). This is precisely what happens when “neutral” laws ignore the “true characteristics of [a] group which act as headwinds to the enjoyment of society’s benefits” (Eaton v. Brant County Board of Education, [1997] 1 S.C.R. 241, at para. 67; Eldridge, at para. 65).

The “animating norm” of the current s. 15 framework guaranteeing substantive equality is also the core value engaged in cases of adverse effects discrimination (Withler, at para. 2; Watson Hamilton and Koshan (2015), at pp. 192 and 197). This Court has never suggested that cases of adverse impact discrimination should be resolved under a different approach (see, for example, Andrews, at pp. 173‑74; Eldridge, at paras. 59‑60; Vriend, at paras. 81‑82 and 87‑89; Law, at paras. 36‑39; Taypotat, at paras. 19‑22; Alliance, at para. 25). On the contrary, we have clarified that the same approach applies regardless of whether the discrimination alleged is direct or indirect. Withler leaves little doubt on this point:

• The substantive equality analysis under s. 15(1) , as discussed earlier, proceeds in two stages . . . . The role of comparison at the first step is to establish a “distinction”.

. . .

• In some cases, identifying the distinction will be relatively straightforward, because a law will, on its face, make a distinction on the basis of an enumerated or analogous ground (direct discrimination) . . . . In other cases, establishing the distinction will be more difficult, because what is alleged is indirect discrimination: that although the law purports to treat everyone the same, it has a disproportionately negative impact on a group or individual that can be identified by factors relating to enumerated or analogous grounds . . . . In that kind of case, the claimant will have more work to do at the first step. Historical or sociological disadvantage may assist in demonstrating that the law imposes a burden or denies a benefit to the claimant that is not imposed on or denied to others. The focus will be on the effect of the law and the situation of the claimant group. [Emphasis added; paras. 61‑62 and 64.]

...

To prove discrimination under s. 15(1) , claimants must show that a law or policy creates a distinction based on a protected ground, and that the law perpetuates, reinforces or exacerbates disadvantage. These requirements do not require revision in adverse effects cases. What is needed, however, is a clear account of how to identify adverse effects discrimination, because the impugned law will not, on its face, include any distinctions based on prohibited grounds (Withler, at para. 64). Any such distinctions must be discerned by examining the impact of the law (Alliance, at para. 25).

This inquiry has frequently been described as a search for a “disproportionate” impact on members of protected groups (see Vriend, at para. 82; Withler, at para. 64; Taypotat, at paras. 21‑23; Action Travail, at p. 1139; Egan v. Canada, [1995] 2 S.C.R. 513, at para. 138, per Cory and Iacobucci JJ. dissenting; Moreau (2010), at p. 154; Braun, at pp. 124‑25; Vizkelety, at p. 176; Watson Hamilton and Koshan (2015), at p. 196; Collins and Khaitan, at pp. 3‑4; Dianne Pothier, “M’Aider, Mayday: Section 15 of the Charter in Distress” (1996), 6 N.J.C.L. 295 at p. 322).

In other words, in order for a law to create a distinction based on prohibited grounds through its effects, it must have a disproportionate impact on members of a protected group. If so, the first stage of the s. 15 test will be met.

How does this work in practice? Instead of asking whether a law explicitly targets a protected group for differential treatment, a court must explore whether it does so indirectly through its impact on members of that group (see Eldridge, at paras. 60‑62; Vriend, at para. 82). A law, for example, may include seemingly neutral rules, restrictions or criteria that operate in practice as “built‑in headwinds” for members of protected groups. The testing requirement in Griggs is the paradigmatic example; other examples include the aerobic fitness requirement in Meiorin, and the policy requiring employees to work on Saturdays in Simpsons‑Sears (see also Central Alberta Dairy Pool v. Alberta (Human Rights Commission), [1990] 2 S.C.R. 489). To assess the adverse impact of these policies, courts looked beyond the facially neutral criteria on which they were based, and examined whether they had the effect of placing members of protected groups at a disadvantage (Moreau (2018), at p. 125).

In other cases, the problem is not “headwinds” built into a law, but the absence of accommodation for members of protected groups (Tarunabh Khaitan, A Theory of Discrimination Law (2015), at p. 77; Dianne Pothier, “Tackling Disability Discrimination at Work: Toward a Systemic Approach” (2010), 4 M.J.L.H 17, at pp. 23‑24). Eldridge is a good example. Under the health care scheme in that case, all patients lacked access to sign language interpreters — but this lack of access had a disproportionate impact on those who had hearing loss and required interpreters to meaningfully communicate with health care providers (paras. 69, 71 and 83).

Disproportionate impact can be proven in different ways. In Eldridge, it was established because “the quality of care received by [those with hearing loss] was inferior to that available to hearing persons” (para. 83 (emphasis added)). In Griggs and Meiorin, by contrast, the relevant impact was the higher rate at which African Americans and women were disqualified from employment. Both are examples of how a law or policy can have a disproportionate impact on members of a protected group. Griggs, Meiorin, and other leading cases leave no doubt that disproportionate impact can be established if members of protected groups are denied benefits or forced to take on burdens more frequently than others. A difference in “quality” of treatment, as in Eldridge, may strengthen a claim of disproportionate impact, but it is not a necessary element (Philipps and Young, at pp. 244‑45; see also Pothier (1996), at p. 322; Selene Mize, “Indirect Discrimination Reconsidered” (2007), N.Z.L. Rev. 27, at p. 39).

Two types of evidence will be especially helpful in proving that a law has a disproportionate impact on members of a protected group. The first is evidence about the situation of the claimant group. The second is evidence about the results of the law.

Courts will benefit from evidence about the physical, social, cultural or other barriers which provide the “full context of the claimant group’s situation” (Withler, at para. 43; see also para. 64). This evidence may come from the claimant, from expert witnesses, or through judicial notice (see R. v. Spence, [2005] 3 S.C.R. 458). The goal of such evidence is to show that membership in the claimant group is associated with certain characteristics that have disadvantaged members of the group, such as an inability to work on Saturdays or lower aerobic capacity (Homer v. Chief Constable of West Yorkshire Police, [2012] UKSC 15, [2012] 3 All E.R. 1287, at para. 14; Simpsons‑Sears; Meiorin, at para. 11). These links may reveal that seemingly neutral policies are “designed well for some and not for others” (Meiorin, at para. 41). When evaluating evidence about the group, courts should be mindful of the fact that issues which predominantly affect certain populations may be under‑documented. These claimants may have to rely more heavily on their own evidence or evidence from other members of their group, rather than on government reports, academic studies or expert testimony.

Courts will also benefit from evidence about the outcomes that the impugned law or policy (or a substantially similar one) has produced in practice. Evidence about the “results of a system” may provide concrete proof that members of protected groups are being disproportionately impacted (Action Travail, at p. 1139; Vizkelety, at pp. 170‑74). This evidence may include statistics, especially if the pool of people adversely affected by a criterion or standard includes both members of a protected group and members of more advantaged groups (Sheppard (2001), at pp. 545‑46; Braun, at pp. 120‑21).

There is no universal measure for what level of statistical disparity is necessary to demonstrate that there is a disproportionate impact, and the Court should not, in my view, craft rigid rules on this issue. The goal of statistical evidence, ultimately, is to establish “a disparate pattern of exclusion or harm that is statistically significant and not simply the result of chance” (Sheppard (2001), at p. 546; see also Vizkelety, at p. 175; Fredman (2011), at pp. 186‑87). The weight given to statistics will depend on, among other things, their quality and methodology (Vizkelety, at pp. 178‑84).

Ideally, claims of adverse effects discrimination should be supported by evidence about the circumstances of the claimant group and about the results produced by the challenged law. Evidence about the claimant group’s situation, on its own, may amount to merely a “web of instinct” if too far removed from the situation in the actual workplace, community or institution subject to the discrimination claim (Taypotat, at para. 34). Evidence of statistical disparity, on its own, may have significant shortcomings that leave open the possibility of unreliable results. The weaknesses with each type of evidence can be overcome if they are both present (Braun, at p. 135; Vizkelety, at p. 192; Vancouver Area Network of Drug Users v. Downtown Vancouver Business Improvement Association (2018), 10 B.C.L.R. (6th) 175 (C.A.), at para. 98). Prof. Colleen Sheppard (2001) recognizes this possibility:

• While in some cases the overwhelming correspondence between certain categories and the gender or racial composition of the category makes the sex or race discrimination claims relatively easy to substantiate, in other cases the statistical preponderance may be less marked. In such cases it may also be important to consider the qualitative components of the harm that constitutes discrimination. [p. 548]

This is not to say, of course, that both kinds of evidence are always required. In some cases, evidence about a group will show such a strong association with certain traits — such as pregnancy with gender — that the disproportionate impact on members of that group “will be apparent and immediate” (Taypotat, at para. 33; see also Fredman (2011), at pp. 187‑88; Sheppard (2001), at pp. 544‑45; Gaz métropolitain inc. v. Commission des droits de la personne et des droits de la jeunesse, 2011 QCCA 1201, at paras. 27 and 47 (CanLII); Oršuš v. Croatia, No. 15766/03, ECHR 2010-II, at para. 153).

Similarly, clear and consistent statistical disparities can show a disproportionate impact on members of protected groups, even if the precise reason for that impact is unknown. Prof. Sandra Fredman has argued forcefully against requiring claimants to specify “the reason why” they are being disadvantaged by a rule or policy:

• To require the complainants to show the ‘reason why’ the PCP [policy, criteria or practice] disadvantages the group as a whole is to fundamentally misunderstand the meaning of indirect discrimination. It is the disparate impact on the group of a PCP itself which constitutes the prima facie discrimination . . . .
• (“Direct and Indirect Discrimination: Is There Still a Divide?”, in Hugh Collins and Tarunabh Khaitan, eds., Foundations of Indirect Discrimination Law (2018), 31, at p. 46; see also Sandra Fredman, “The Reason Why: Unravelling Indirect Discrimination” (2016), 45 Indus. L.J. 231.)

I agree. If there are clear and consistent statistical disparities in how a law affects a claimant’s group, I see no reason for requiring the claimant to bear the additional burden of explaining why the law has such an effect. In such cases, the statistical evidence is itself a compelling sign that the law has not been structured in a way that takes into account the protected group’s circumstances (see Fredman (2011), at p. 181; Vizkelety, at pp. 174‑76; Action Travail, at p. 1139).

...

Some further observations.

First, whether the legislature intended to create a disparate impact is irrelevant (Sheppard (2001), at pp. 543‑44; Watson Hamilton and Koshan (2015), at pp. 196‑97; Faraday, at p. 310). Proof of discriminatory intent has never been required to establish a claim under s. 15(1) (Andrews, at pp. 173‑74; Eldridge, at para. 62; Vriend, at para. 93; Alliance, at para. 28; Centrale, at para. 35). Nor is an ameliorative purpose sufficient to shield legislation from s. 15(1) scrutiny (Centrale, at paras. 8 and 35; Alliance, at paras. 32‑33).

Second, if claimants successfully demonstrate that a law has a disproportionate impact on members of a protected group, they need not independently prove that the protected characteristic “caused” the disproportionate impact (Tarunabh Khaitan and Sandy Steel, “Wrongs, Group Disadvantage and the Legitimacy of Indirect Discrimination Law”, in Hugh Collins and Tarunabh Khaitan, eds., Foundations of Indirect Discrimination Law (2018), 197, at pp. 203-4 and 220; Fredman (2018), at p. 46; Braun, at p. 146; Watson Hamilton and Koshan (2015), at p. 197; West Yorkshire Police, at paras. 12‑14; Essop, at paras. 24‑27). Put differently, there was no need for the claimant in Griggs to address whether his exclusion was based on his race or lack of a high school education. The whole point of the adverse impact analysis was to show that the use of a high school education as a criteria for employment had a disproportionate impact on African Americans (Fredman (2011), at p. 189).

It is also unnecessary to inquire into whether the law itself was responsible for creating the background social or physical barriers which made a particular rule, requirement or criterion disadvantageous for the claimant group. Returning to Griggs, this would amount to asking whether Duke Power Co. was responsible for lower rates of high school education among African Americans. Plainly, it was not — but this was entirely irrelevant to whether a disproportionate impact had been established. Section 15(1) has always required attention to the systemic disadvantages affecting members of protected groups, even if the state did not create them (Alliance, at para. 41; Centrale, at para. 32; Vriend, at paras. 84 and 97; Eldridge, at paras. 64‑66; Eaton, at para. 67; R. v. Turpin, [1989] 1 S.C.R. 1296, at pp. 1331‑32).

Third, claimants need not show that the criteria, characteristics or other factors used in the impugned law affect all members of a protected group in the same way. This Court has long held that “[t]he fact that discrimination is only partial does not convert it into non‑discrimination” (Brooks v. Canada Safeway Ltd., [1989] 1 S.C.R. 1219, at p. 1248, quoting James MacPherson, “Sex Discrimination in Canada: Taking Stock at the Start of a New Decade” (1980), 1 C.H.R.R. C/7, at p. C/11). In Brooks, the Court held that a corporate plan which denied benefits to employees during pregnancy discriminated on the basis of sex. The employer argued that the plan did not deny benefits to “women”, but only to “women who are pregnant” (p. 1248, quoting MacPherson, at p. C/11). Writing for the Court, Dickson C.J. explained that practices amounting to “partial discrimination” are no less discriminatory than those in which all members of a protected group are affected (pp. 1247‑48).

...

In sum, then, the first stage of the s. 15 test is about establishing that the law imposes differential treatment based on protected grounds, either explicitly or through adverse impact. At the second stage, the Court asks whether it has the effect of reinforcing, perpetuating, or exacerbating disadvantage (Alliance, at para. 25).

Where possible, the two inquiries should be kept distinct, but there is clearly potential for overlap in adverse effects cases based on “the impossibility of rigid categorizations” (Sheppard (2010), at p. 21). What matters in the end is that a court asks and answers the necessary questions relevant to the s. 15(1) inquiry, not whether it keeps the two steps of the inquiry in two impermeable silos.

...

In my view, the appropriate remedy is a declaration that there has been a breach of the s. 15(1) rights of full‑time RCMP members who temporarily reduced their working hours under a job‑sharing agreement, based on the inability of those members to buy back full pension credit for that service. The methodology for facilitating the buy‑back of pension credit is for the government to develop, but any remedial measures it takes should be in accordance with this Court’s reasons. They should also have retroactive effect in order to give the claimants in this case and others in their position a meaningful remedy (Vancouver (City) v. Ward, [2010] 2 S.C.R. 28, at para. 20; Doucet‑Boudreau v. Nova Scotia (Minister of Education), [2003] 3 S.C.R. 3, at paras. 55‑58)."

Justices Brown and Rowe (in joint dissenting reasons) wrote as follows (at paras. 140-143, 145-146, 174, 178-181, 195, 207, 209, 216, 220, 227):

"At one level, this appeal presents the simple question: is tying pension benefits to hours worked discriminatory? The Royal Canadian Mounted Police (“RCMP”) allows two or more of its regular members (“members”) to share one full‑time position through the option of “job‑sharing.” The pension benefits of members who job‑share, like all other members, are determined through the Royal Canadian Mounted Police Superannuation Act, R.S.C. 1985, c. R‑11 and the Royal Canadian Mounted Police Superannuation Regulations, C.R.C., c. 1393 (collectively, the “Plan”). Under the Plan, the pension benefits of members who job‑share are prorated to reflect the hours they worked during the job‑sharing period.

In addition to job‑sharing, the RCMP has also given its members the option of taking leave without pay (“LWOP”). These members may “buy back” pension benefits when they return to work from an extended period of LWOP.

Through its job‑sharing policy and the LWOP provisions, the RCMP has sought to provide flexible working arrangements in recognition of the burden women face in pursuing a career due to the unequal distribution of childcare responsibilities in society. For members with childcare responsibilities, job‑sharing accommodates those who are able to remain operationally connected to the force and want to keep their policing skills up to date, while LWOP accommodates those who temporarily leave the force by enhancing their ability to return to work without undue financial hardship. The Plan and the RCMP’s policy on job‑sharing are not anathema to the vision of equality that underlies s. 15 of the Canadian Charter of Rights and Freedoms , but instead represent an attempt to accommodate employees in light of their particular circumstances.

And yet, our colleague Abella J. finds these aspects of the Plan to be unconstitutional. She describes the historical disadvantages women have faced in the workplace and then concludes, in effect, that the Plan does not do enough to remedy these disadvantages. One may reach this conclusion as a matter of policy, but that is not the question to be decided. Rather, and at its most fundamental level, it is whether, as a matter of law, the Constitution empowers (or even requires) the courts to substitute their views as to how to remedy those disadvantages for those of the legislature and the executive.

...Among other things, it effectively overrules this Court’s recent statement in Alliance that the state may “act incrementally in addressing systemic equality” (para. 42 (emphasis added)). That the Plan does not eradicate disadvantage should not mean that it should attract censure as “discriminatory.” Rather, considered in its entirety and with proper attention to its object, the Plan is a package of benefits designed to balance the needs of some RCMP employees during their child‑raising years, prorated according to hours worked. On any permutation of s. 15(1) , its effect surely cannot be to hinder government efforts to address pre‑existing inequality.

This leads to a more fundamental concern presented by this appeal — a concern which, we observe, has been repeatedly made by legal commentators, but which has yet to be taken up by this Court. The gauge of “substantive equality” by which this Court has measured s. 15(1) claims of right, not having been defined (except by reference to what it is not — e.g. “formal equality”), has become an open‑ended and undisciplined rhetorical device by which courts may privilege, without making explicit, their own policy preferences. As we explain below, and with respect, this case is an instance of that inherent malleability being deployed so as to strike down a scheme which was, after all, designed to be ameliorative.

...

Our colleague identifies a distinction between job‑sharers and full‑time members who work regular hours, who are suspended or who take LWOP (while failing, as noted, to consider individuals who work part‑time prior to taking LWOP) (paras. 25 and 83). Yet, she later rejects (at least facially) a comparison to members who take LWOP, dismissing it as a “formalistic” and “mirror comparator group” analysis (at paras. 93‑94), maintaining that job‑sharers are entitled to substantive equality relative to full‑time members (para. 94). As we explain below, however, it becomes evident upon closer examination that her rejection of a comparison to members who take LWOP is only superficial. The existence of the buy‑back provisions for members who take LWOP is the very reason that she finds a breach; absent that basis for comparison, the alleged breach disappears.

...

Our colleague overcomes the requirement of causation, and these statements, by relaxing the claimant’s evidentiary burden to the point of insignificance. She posits that “evidence of statistical disparity and of broader group disadvantage may demonstrate disproportionate impact,” although she adds that “neither is mandatory and their significance will vary depending on the case” (para. 67 (emphasis added)). With respect to “broader group disadvantage,” a single claimant’s “own evidence,” or even judicial notice, is all she requires (paras. 57 and 66‑67). While courts must evaluate evidence in light of “the proof which it was in the power of one side to have produced, and in the power of the other to have contradicted” (Snell v. Farrell, [1990] 2 S.C.R. 311, at p. 328, quoting Blatch v. Archer (1774), 1 Cowp. 63, 98 E.R. 969, at p. 970), ultimately the onus is on the claimant to establish causation. In many contexts, subjective anecdotal evidence is simply incapable of meeting this objective onus (e.g. Taypotat, at paras. 33‑34; Auton (Guardian ad litem of) v. British Columbia (Attorney General), 2004 SCC 78, [2004] 3 S.C.R. 657, at paras. 58 and 62; Gosselin v. Quebec (Attorney General), 2002 SCC 84, [2002] 4 S.C.R. 429, at paras. 8 and 47). Our colleague’s relaxed approach also risks overlooking the interests of the public good (B. W. Miller, “Majoritarianism and Pathologies of Judicial Review”, in G. Webber et al., Legislated Rights: Securing Human Rights through Legislation (2018), 181, at p. 196).

With respect to statistical disparity, our colleague contends that “clear and consistent statistical disparities can show a disproportionate impact on members of protected groups, even if the precise reason for that impact is unknown” (para. 62). In this case, then, because there is a statistical disparity between women and men with respect to who has taken advantage of the job‑sharing program, and because there is evidence that women have historically borne a greater part of childcare responsibilities and formed a greater proportion of the part‑time labour force, she finds that the law has a disproportionate impact on women (paras. 97‑106).

With respect, this analysis is unsound, since it assumes that correlation between the number of women who have taken advantage of the job‑sharing program and evidence of disproportionate childcare responsibilities falling upon women is the function of causation, whereas it might well be the function of independent factors. Correlation itself is not proof of causation. Indeed, where one is dealing with complex social and economic considerations, like sex and employment, one can readily assume that there are many factors involved, some of which will give rise to causation while others will simply be the result of coincidence (that is, caused by independent factors).

But it is causation that must be demonstrated between the law and the disadvantage. It is not enough for our colleague to refer to a statistical disparity and a broader group disadvantage. Indeed, the presence of a statistical disparity is precisely what is to be expected where a law is enacted, as the relevant portions of the Plan were, to incrementally narrow a pre‑existing systemic disadvantage. When the law fails to completely eradicate such disadvantage, an element of disparity will obviously remain. It follows that to accept statistical disparity and broader group disadvantage as sufficient to demonstrate that a law creates a distinction in impact is to do away with this Court’s statement made only two years ago in Alliance that s. 15 neither imposes “a freestanding positive obligation on the state to . . . redress social inequalities” nor “undermine[s] the state’s ability to act incrementally in addressing systemic inequality” (para. 42). It would also represent an undisciplined judicial expansion of the scope of s. 15, which does not apply to private acts of discrimination, because it would render the state responsible for discrimination it has not caused.

...

Our colleague’s removal of considerations of arbitrariness or unfairness from the s. 15 analysis has far‑reaching consequences for this appeal. As we identified above, a distinction arises based on sex when comparing members who job‑sharing to members with male pattern employment, that is, members who work 40‑hour weeks throughout their careers. Because the pension benefits of members in the job‑sharing program are prorated to reflect the lower number of hours they worked, they receive a lower level of pension benefits than members with a male pattern of employment.

...

Governments must be afforded the latitude to act incrementally when addressing a deeply ingrained, complex and persistent social phenomenon such as inequality. (This assumes that the inequality arises from factors in society; where the government itself has created the inequality, matters are, as we have already indicated, somewhat different.) There are processes by which a government must set its priorities, allocate its budget, and obtain parliamentary approval of its programs. In designing legislation to address a particular equality issue, a government can draw on far more internal and external expertise than we judges can. As a result, it is better positioned than we are to appreciate the consequences of a particular course of law‑making, both upon society and upon public resources. With these practical realities in mind, we must also recognize that, were a government expected to remove all inequalities for all groups on every occasion it acted, it may be disinclined to act, given that any remedial scheme will inevitably be under‑inclusive in some respect. Governments would, understandably, become “reluctant to create any new [remedial] benefit schemes because their limits would depend on an accurate prediction of the outcome of court proceedings under s. 15(1) of the Charter ” (Egan v. Canada, [1995] 2 S.C.R. 513, at para. 104, per Sopinka J.).

...

At the risk of repeating ourselves, we stress that, as recently as two years ago in Alliance, the Court affirmed this commitment to judicial restraint by permitting the government to address pre‑existing disadvantage incrementally (para. 42). And it also bears repeating that Alliance stated that, first, there is no freestanding positive obligation to remedy social inequities, and secondly, that the state is entitled to act incrementally to address such inequities.

...

A related and final point on the practical implications of our colleague’s decision. For 30 years, this Court has struggled to define the term “substantive equality.” An intelligible and principled definition continues to be elusive. Indeed, this case illustrates the difficulties posed by the slippery quality of “substantive equality” — the core value of our colleague’s decision (at paras. 47‑48) — and its constant shifting in this Court’s jurisprudence.

...

The result of all this is corrosive of the rule of law. Our colleague wonders aloud what our definition of the rule of law is (para. 135). We share the views of jurists such as Lord Bingham and Sharpe J.A.: the concept of the rule of law has interlocking components (see T. Bingham, The Rule of Law (2010), at pp. 160‑70; R. J. Sharpe, Good Judgment: Making Judicial Decisions (2018), at pp. 122‑24). One is pertinent here: Canadians should be governed by rules, stated and knowable in advance, that enable them to guide their conduct. As Sharpe J.A. writes:

• . . . the [Supreme] [C]ourt has insisted that there must be an intelligible standard, capable of providing “an adequate basis for legal debate . . . as to its meaning by reasoned analysis applying legal criteria.”
• In Irwin Toy . . . the majority wrote that . . . . “[w]here there is no intelligible standard” and where the decision‑maker has been “given a plenary discretion to do whatever seems best in a wide set of circumstances,” the essential minimum requirements of the rule of law are not met.

• (p. 123, quoting R. v. Nova Scotia Pharmaceutical Society, [1992] 2 S.C.R. 606, at p. 639; Irwin Toy Ltd. v. Quebec (Attorney General), [1989] 1 S.C.R. 927, at p. 983)

...

Indeed, more telling than what our colleague does say in response is what she does not say. Notably, she does not explain what “substantive equality” means (save by reference to what it is not — “formal equality”). She fails to define “substantive equality” in terms that allow its meaning to be understood so that the requirements of s. 15 can be practically knowable and reasonably predictable in advance. Thus loosely defined, substantive equality is almost infinitely malleable, allowing judges to invoke it as rhetorical cover for their own policy preferences in deciding a given case. Such vast and little‑bounded discretion does not accord with, but rather departs from, the rule of law."

Justice Côté (also in dissent) wrote as follows (at paras. 231, 253, 255):

"Discrimination on the basis of sex is of the most invidious order. Like race, sex is an innate and immutable characteristic, and bears no relevant relationship to capability. Without question, women have faced a prolonged fight for equal treatment under the law, a fight marked by a society where women have historically been disadvantaged and where they continue to be so today: Public Service Alliance of Canada v. Canada (Department of National Defence) (C.A.), [1996] 3 F.C. 789, at para. 16; Quebec (Attorney General) v. Alliance du personnel professionnel et technique de la santé et des services sociaux, 2018 SCC 17, [2018] 1 S.C.R. 464. But that is not the question before this Court. Nor is the question before this Court whether the impugned legislative provisions are irrational, illogical, or even under-inclusive — that a law is not perfect, or even excludes some, does not make it per se unconstitutional: Gosselin v. Quebec (Attorney General), 2002 SCC 84, [2002] 4. S.C.R. 429, at para. 55; Andrews v. Law Society of British Columbia, [1989] 1 S.C.R. 143, at pp. 168-69. Rather, over the course of three decades, this Court has carefully crafted a test to assess whether a particular form of alleged discrimination is discrimination in fact and runs afoul of the guarantee of equal treatment under the law found in s. 15 of the Canadian Charter of Rights and Freedoms . A crucial element of s. 15(1) of the Charter is that it enumerates the grounds of discrimination that fall within its constitutional prohibition. Here, with respect, I cannot agree with my colleagues that the impugned provisions of the pension plan create a distinction on the basis of the enumerated ground of sex.

...

In this sense, I wish to add one final point on the role of the judiciary vis‑à‑vis the role of the legislature. The result the majority reaches may certainly be desirable insofar as it guarantees the opportunity for increased pension benefits to RCMP members who job-share. But when the Court reaches this result in such a doctrinally precarious fashion, and when and if the impugned provisions are illogical, irrational, or under‑inclusive, then it is the legislature’s role to rectify — the remedy does not lie in the Constitution, which proscribes particular forms of discrimination, forms that do not exist here. With the greatest respect, then, the remedy sought in the case at bar should be granted by the democratic process.

...Further, I write separately in order to highlight the under-inclusive nature of the pension plan, which disproportionately affects all those with caregiving responsibilities, including same-sex couples with children and individuals with caregiving responsibilities for their aging partners or parents. It therefore falls to the legislature, not the courts, to remedy any under-inclusiveness in this legislation, which was purportedly meant to assist with caregiving responsibilities in the first place."

Note: The summary and body are drawn from Eugene Meehan’s SupremeAdvocacy Weekly Updates for the Law Community.