Ancient Greeks wondered whether it was possible to construct a square of the same area as a given circle using only a compass and a ruler ― to square the circle. The problem occupied some great minds of that age and of the subsequent ones, even Napoleon apparently. It took well over two millennia until it was shown to be impossible to solve. Public law has its own quadrature problem, posed by A.V. Dicey (the first edition of whose Introduction to the Study of the Law of the Constitution came out just a couple of years after the demonstration of the impossibility of squaring the circle): it consists in fitting together, albeit by means of verbal rather than geometrical contortionism, parliamentary sovereignty and the Rule of Law.
Dicey and many others since him have mostly been preoccupied by this problem in the context of fundamental individual rights, and their protection from a legislature unconstrained by a supreme law constitution. Canada eventually abandoned this attempt ― or rather cut back on it significantly, since some rights, such as that to property, remain unprotected by the Canadian Charter of Rights and Freedoms. But, to an extent that Dicey did not imagine and that is arguably without parallel in the rest of the Commonwealth, we have re-deployed our intellectual energies merely to a different application of the same problem, this one in administrative law. We are struggling to reconcile parliamentary sovereignty, which suggests giving effect to legislative attempts to insulate administrative decision-makers from judicial review, and the Rule of Law, which, as Dicey himself suggested, requires courts of justice to apply the law. We are not succeeding.
It is not for lack of trying. The majority opinion in the supposedly still-leading case on judicial review of administrative action, Dunsmuir v New Brunswick, 2008 SCC 9,  1 SCR 190, recognized that
[j]udicial review seeks to address an underlying tension between the rule of law and the foundational democratic principle, which finds an expression in the initiatives of Parliament and legislatures to create various administrative bodies and endow them with broad powers. 
Dunsmuir and the subsequent cases that have
fucked up beyond all recognition refined the framework that it laid down attempted to resolve this tension and to make sure that, as a Russian saying has it, the wolves are sated, and the sheep unharmed. Scholarly commentary has worked, I think, in the same direction.
The most recent example is a thoughtful post on ABlawg by Martin Olszynski. Professor Olszynski seeks to recover what he sees as Dunsmuir’s promise of reconciling parliamentary sovereignty and the Rule of Law. He proposes to achieve this by making
two inter-related changes to the Dunsmuir framework … The first change would be to reverse the presumption of reasonableness on questions of law to a presumption of correctness, which can then be rebutted for the large majority of such questions through the presence of a privative clause (this approach would be similar to that proposed by Justice Deschamps in Dunsmuir). The second related change would be to abandon the overly broad and fundamentally contradictory concept of “expertise” as a basis for deference and to replace it with the potential for democratic accountability, which ultimately is the basis for legislative supremacy.
Although the judiciary has the “training, independence, and impartiality” to claim “the upper hand in the interpretation of the law”, it ought to yield this upper hand to legislative statements that call for deference to administrative decision-makers. Legislatures “must be respected – because they are democratically elected and accountable”. Provided they make themselves sufficiently clear by enacting “privative clauses” (provisions that typically seek to out judicial review of administrative decisions or to strictly limit it), legislatures can be made to answer for any decision to remove legal interpretation from the purview of the courts. When the legislation includes a privative clause, a reviewing court should, therefore, defer, but not otherwise ― and especially on the pretense that an administrative decision-maker is an expert by virtue of its very existence.
I agree with Professor Olszynski’s criticism of the role that the idea of administrative expertise has come to play in Canadian administrative law (which I have not fully summarized ― you really should read it). Last year I wondered here whether “the Supreme Court is embracing that pop-psychology staple about 10,000 hours of doing something being enough to make one master it”, and I elaborate on my worries about “expertise” in a paper I recently presented at the TransJus Institute of the University of Barcelona. I also agree that courts should not be shrinking violets when it comes to legal interpretation. It’s their job, and it’s the think that they’re supposed to be good at. If legislatures decide to scrap some of the administrative bodies they have set up (a guy can dream, right?), the courts will have to apply the legislation these bodies are now responsible for. They ought to be able to do that.
But I am skeptical of Professor Olszynski’s suggestion that the presumption that questions of law must be addressed by courts should, in the name of democratic accountability, by rebutted by privative clauses. Indeed, I think that the idea of democratic accountability is not readily applicable in this context. Professor Olszynski argues that accountability works by pointing to his own criticism of the application of a privative clause in an environmental law case, and contrasting it with the fact “that few labour or employment lawyers would argue against privative clauses in that context”. With respect, the possibility of academic criticism does not make for democratic accountability; nor does acceptance by a relevant expert community (if indeed “labour and employment lawyers” are the relevant expert community in relation to labour law ― what about economists, for instance?) make for democratic legitimacy. How many voters have ever heard of privative clauses, never mind being able to articulate any thoughts on their desirability? To believe that legislatures can, let alone will, be held accountable for eliminating the courts’ role in legal interpretation unwisely, or even abusively, requires more optimism than I could ever muster.
I am inclined to think ― though my thoughts on administrative law are still tentative ― that in determining the standard of review we should not attempt to reconcile the Rule of Law and legislative supremacy. The reconciliation is never meant to be real in any case. The Rule of Law is, ultimately, the dominant value, because even those who claim that they want to respect legislative will refuse to give effect even to the clearest privative clauses. To take a statutory provision that says “no judicial review” to mean “deferential judicial review” is not to accede to the legislature’s desires, but to impose one’s own principles ― including the principle of the Rule of Law ― on it.
And there is nothing wrong with this. The Rule of Law, as the Justice Rand observed ― in the context of a lawless exercise of administrative power ― in Roncarelli v Duplessis,  SCR 121 at 142, is “a fundamental postulate of our constitutional structure”. It is a constitutional principle that can, as the Supreme Court recognized in Reference re Secession of Quebec,  2 SCR 217, result in “substantive limitations upon government action” ― including, relevantly to us here, in government action aiming at reducing the courts’ powers of judicial review. By contrast, as the Secession Reference also recognized, democracy ― whether direct democracy, which was at issue in that opinion, or representative democracy, and whether accountable or otherwise ― must be confined by constitutional limitations. The Court wrote “that with the adoption of the Charter, the Canadian system of government was transformed to a significant extent from a system of Parliamentary supremacy to one of constitutional supremacy”.  But that’s not quite right. The Charter imposed additional restrictions on legislatures, but it did not “transform” the constitutional system, which was already one of “constitutional supremacy” under the Constitution Act, 1867.
To the extent that it is required by the Rule of Law principle, judicial review of administrative action, including correctness review on questions of law, is a constitutional requirement. This extent is the question that Canadian administrative lawyers and judges should be addressing. Virtually everyone, I think, agrees that the Rule of Law requires correctness review in at least some cases. My own inclination is to say that it requires correctness review often, and perhaps always. I might be wrong about that, but if I am, this is because I misunderstand the Rule of Law, not because I fail to account for Parliamentary sovereignty and to give effect to (modified versions of) privative clauses. There is simply no need to bring parliamentary sovereignty into the standard of review equation, thereby making it unsolvable. Unlike in mathematics, the impossibility of squaring the public law circle cannot be conclusively demonstrated (though even in mathematics the demonstration apparently did not stop enthusiasts from trying). But the futility of well over a century’s worth of attempts should, I submit, be a warning to us all.