The greatest challenge facing the Supreme Court of Canada is the risk of its politicization, understood … as a form of adjudicative practice that is not governed by legal rules, legal principles, or other legal norms and that does not restrict itself to deciding justiciable questions.
Whether or not “politicization” is the best possible label for this sort of adjudication, and whether or not it is the greatest challenge facing the Supreme Court ― both plausible but debatable propositions ― I agree that the danger Prof. St-Hilaire identifies is a serious one. It is a challenge, moreover, not only for the Court, or even the judiciary as a whole, but for the legal profession, which is too readily supportive of adjudication that does not abide by the requirements of the Rule of Law.
However, precisely because this is a very serious issue, it is important to be careful in circumscribing it ― not to accuse the Supreme Court of being “political” or disregarding the Rule of Law when it is not. And here, I part company with Prof. St-Hilaire to some extent. Some of the specific instances of politicization that he identifies are indeed examples of the Court failing to act judicially or to uphold the law. Others, in my view, are not.
I agree with Prof. St-Hilaire’s criticism of the Supreme Court’s theoretical embrace of living constitutionalism in theory ― and its practical embrace of interpretive eclecticism with few if any principles to constrain cherry-picking interpretive approaches. If, in other jurisdictions, there is such a thing as a “law of interpretation” (to borrow the title of a recent article by William Baude and Stephen E Sachs), constitutional interpretation in Canada seems to be largely lawless, as most recently highlighted by Benjamin Oliphant. Indeed, I would go further than Prof. St-Hilaire (if I understand him correctly), and argue that judges ought to be originalists in order to uphold the principles of the Rule of Law and constitutionalism, because, as Jeffrey Pojanowski argues,
if one does not seek to identify and treat the original law of the constitution as binding, one imperils the moral benefits constitutionalism exists to offer the polity. We are back to square one, adrift in a sea of competing, unentrenched norms.
I share Prof. St-Hilaire’s unease at the Supreme Court’s often unprincipled practice of suspending declarations of invalidity of legislation. While I once argued that this device had some redeeming virtues, the Court’s failure to articulate and apply coherent principles for deploying it nullifies these virtues. As things currently stand, the Court’s approach to suspended declarations of unconstitutionality is yet another manifestation of the sort of uncabined discretion that is antithetical to the Rule of Law.
I also agree with Prof. St-Hilaire that the Supreme Court’s approach to review of allegedly unconstitutional administrative decisions under the framework set out in Doré v Barreau du Québec, 2012 SCC 12,  1 SCR 395 is a “denial of constitutional justice”. (That said, it is worth noting that the Court’s application of this framework is a mess, and it might matter less than the Court itself suggests ― though is a Rule of Law problem in its own right.) And I agree with Prof. St-Hilaire’s criticisms of the Court’s approach to s 15 of the Canadian Charter (including because it is flatly inconsistent with its original meaning, as Justice Binnie, among others, openly recognized).
Now on to some of my disagreements with Prof. St-Hilaire. Some of them we have already canvassed at some length. I remain of the view (previously expressed here) that judges can, in appropriate cases, criticize the legitimacy of their colleagues’ adjudicative techniques. Indeed, I am puzzled by prof. St-Hilaire’s insistence on the contrary. Can a judge who agrees with his critique of the Supreme Court not say so? I also remain of the view, that courts can, subject to usual rules on justiciability, pronounce on constitutional conventions, which are not essentially different from legal rules. I most recently expressed and explained this view in a post here criticizing the UK Supreme Court’s decision in R (Miller) v Secretary of State for Exiting the European Union,  UKSC 5, and in this short article for a special issue of the Supreme Court Law Review.
New, to this space at least, is my disagreement with Prof. St-Hilaire on the scope of the doctrine of res judicata and the force of stare decisis. Prof. St-Hilaire accuses the Supreme Court of “conflating the two principles”, and of playing fast and loose with both. In his view, stare decisis is about “the general/indirect jurisprudential authority of judicial reasons”, while res judicata concerns “the particular/direct authority of judicial decisions per se, and taken separately”. When the Supreme Court upheld the constitutionality of the criminalisation of assisted suicide in Rodriguez v. British Columbia (Attorney General),  3 SCR 519, that rendered the matter res judicata, and should have prevented the courts, including the Supreme Court itself, from revisiting the matter, as they eventually did in Carter v Canada (Attorney General), 2015 SCC 5,  1 SCR 331. More broadly, the Supreme Court has been too cavalier with precedent, in particular in the area of labour law.
I agree with Prof. St-Hilaire that the Supreme Court has in some cases ― especially those concerning the purported constitutional rights of labour unions ― disregarded precedent without any compelling reason to do so. For reasons best explained, I think, by Jeremy Waldron, a fairly robust version of stare decisis is an important component of the Rule of Law. However, in my view, prof. St-Hilaire takes this point much too far. For my part, I am content to accept the Supreme Court’s explanation in Canada (Attorney General) v Confédération des syndicats nationaux, 2014 SCC 49,  2 SCR 477 that “res judicata … require[s] that the dispute be between the same parties”, as well as on the same issue, while stare decisis is the broader ― and more flexible ― principle that applies “when the issue is the same and that the questions it raises have already been answered by a higher court whose judgment has the authority of res judicata“.  This is not merely a terminological dispute. The point is that courts should be able to reverse their own decisions, albeit with the greatest circumspection.
Without fully defending my views, I would argue that the criteria set out in Canada (Attorney General) v Bedford, 2013 SCC 72,  3 SCR 1101 are a sound guideline, provided that they are rigorously applied (which they were not in the labour union cases). Precedent, the Court held,
may be revisited if new legal issues are raised as a consequence of significant developments in the law, or if there is a change in the circumstances or evidence that fundamentally shifts the parameters of the debate. 
I think this is right, because while the stability of the law, its diachronic coherence, is very important, the law’s consistency at any given time point, its ability to remain a “seamless web”, or synchronic coherence, is important too, and also a requirement of the Rule of Law. These two dimensions of legal coherence are in tension, and sometimes in conflict, and I think it is a mistake to say, as I take it Prof. St-Hilaire does, that diachronic coherence must always prevail. Perhaps more controversially, I am inclined to think that there is also a case to be made for the proposition that the Rule of Law can accommodate, if it does not positively require, departures from precedent that serve to make the law make sense in light of changed circumstances and evidence. The ideas of non-arbitrariness and congruence between the law on the books and its real-world application at least point in that direction, though the argument would be worth developing in more detail.
I will end where Prof. St-Hilaire begins: with judicial appointments. (Of course, the process of appointment is not part of adjudication. But it makes sense to consider it in a discussion of the danger of the politicization of the Supreme Court, even though it doesn’t fit within Prof. St-Hilaire’s definition of that term.) Prof. St-Hilaire criticizes the inclusion of “parliamentary consultation” in the appointment process, and I agree with him to that extent. However, I do not share the main thrust of his comments, which is that we need to move “from more political criteria to increasingly professional criteria in the selection of” Supreme Court judges. Political control over judicial appointments is an important check on the power of the courts, as well as an indispensable means to inject some much needed ideological diversity into the judiciary. The current judiciary and legal profession are too homogeneous ― in their thinking, not (only) their skin colour ― for a “professional” appointments process to produce a judiciary that does not all believe the same pieties (including pieties about living constitutionalism and other things that Prof. St-Hilaire criticizes!). That said, since politicians should have the responsibility for judicial appointments, it is also politicians who should be held accountable for them. As Adam Dodek has suggested, the Justice Minister who should appear before Parliament to explain the government’s choice of Supreme Court judges ― but not (and here, I take it, I part company with prof. Dodek) the new judges themselves.
I share Prof. St-Hilaire’s view that “the Supreme Court must choose principle over politicization”. I am looking forward to the Runnymede Society’s forthcoming conference at which this call will no doubt be much reiterated ― including by yours truly. That said, though it reflects a nice sentiment, an appeal to principle over politics does not tell us very much. It leaves open both the question of what principles one should adopt, and of counts as objectionable politicization rather than mere good faith error. Prof. St-Hilaire and I disagree about that to some extent, as I have endeavoured to show. The debate must, and will, continue, and we should have no illusions about settling it with high-minded slogans.