Here are the main uses of “guardian(s) of the Constitution” in UK-related courts. I asterisk sentences that seem to me fallacious.
1 In Akar v AG Sierra Leone  AC 853 at 872, Lord Guest, dissenting, said:
Although the courts are the guardians of the Constitution, I believe that in interpreting the Constitution the ground has to be trod warily and with great circumspection….873…If the courts are precluded from inquiry into the justifiability of executive acts [on grounds such as reasonableness, policy, sense or other grounds apart from vires and good faith] a fortiori it appears to me that the court cannot inquire into the validity of an Act of Parliament which ex facie appears to be within the Constitution.
2 In Khan v Trinidad & Tobago  UKPC 79,  AC 374 Lord Steyn, dissenting in the Judicial Committee, said:
In Hunter v Southam Inc  2 SCR 145, 155 Dickson CJ of the Canadian Supreme Court explained:
The task of expounding a constitution is crucially different from that of construing a statute. A statute defines present rights and obligations. It is easily enacted and as easily repealed. A constitution, by contrast, is drafted with an eye to the future. Its function is to provide a continuing framework for the legitimate exercise of governmental power and, when joined by a Bill or a Charter of Rights, for the unremitting protection of individual rights and liberties. Once enacted, its provisions cannot easily be repealed or amended. It must, therefore, be capable of growth and development over time to meet new social, political and historical realities often unimagined by its framers.* The judiciary is the guardian of the constitution and must, in interpreting its provisions, bear these considerations in mind.
In the Privy Council in Edwards v Attorney General for Canada  AC 124, 136, Lord Sankey LC expressed the same idea by saying that a Constitution should be approached as “a living tree capable of growth and expansion within its natural limits”.
3 In Mathew v Trinidad & Tobago  UKPC 33;  1 AC 433, Lord Nicholl, dissenting, at  repeated the dictum of Dickson CJ without the truncation made by Lord Steyn:
…. A constitution, by contrast [with statute], is drafted with an eye to the future. Its function is to provide a continuing framework for the legitimate exercise of governmental power and, when joined by a Bill or a Charter of Rights, for the unremitting protection of individual rights and liberties. Once enacted, its provisions cannot easily be repealed or amended. It must, therefore, be capable of growth and development over time to meet new social, political and historical realities often unimagined by its framers. The judiciary is the guardian of the Constitution and must, in interpreting its provisions, bear these considerations in mind. Professor Paul Freund expressed this idea aptly* when he admonished the American courts “not to read the provisions of the Constitution like a last will and testament lest it become one”.
4 In SB (India) v Home Secretary  EWCA Civ 451;  4 W.L.R. 103, at , Gloster LJ for the Court of Appeal quoted (without approval or disapproval) the Upper Tribunal quoting an Indian Supreme Court judgment in 2013:
…Justice KS Radhakrishnan in his judgment in NLSA said this: ‘119. The role of the court is to understand the central purpose and theme of the Constitution for the welfare of the society. Our Constitution, like the law of the society, is a living organism.* It is based on a factual and social reality that is constantly changing. Sometimes a change in the law precedes societal change and is even intended to stimulate it. Sometimes, a change in the law is the result in the social reality. … It is the denial of social justice which in turn has the effect of denying political and economic justice … 122. It is now very well recognized that the Constitution is a living character; its interpretation must be dynamic.* It must be understood in a way that intricate [sic] and advances modern reality.* The judiciary is the guardian of the Constitution and by ensuring to grant legitimate right that is due to TGs [‘transgender’ persons], we are simply protecting the Constitution* and the democracy inasmuch as judicial protection and democracy in general and of human rights in particular* is a characteristic of our vibrant democracy.
5 To these, add by way of explanatory supplement, the oft-repeated dictum of the Judicial Committee in Attorney General of Trinidad and Tobago v Whiteman  2 AC 240, 247:
The language of a Constitution falls to be construed, not in a narrow and legalistic way, but broadly and purposively, so as to give effect to its spirit, and this is particularly true* of those provisions which are concerned with the protection of human rights.
But, against the asterisked sentences: How can the fact that the framers and the people have deliberately made their Constitution harder to amend than statutes be justification for the judicial/academic conclusion that therefore the Constitution must be more easily revisable by judges than statutes and common law rules are? And why should rights be interpreted generously and expansively when doing so entails that duties, constraints and/or harms are expansively imposed on other persons? Why should there be a bias towards change and enumerated rights rather than stability, respect for expectations, and upholding of other enumerated or unenumerated liberties and vital interests? Why not an over-arching principle of even-handedness and fidelity to law in adjudication?
Professor John Finnis FBA QC (Hon) is Professor Emeritus of Law & Legal Philosophy in the University of Oxford and Biolchini Family Professor of Law at the University of Notre Dame. Between 1972 and 1989 he was Rhodes Reader in the Laws of the British Commonwealth and the United States in the University of Oxford. In 2011, Oxford University Press published five volumes of his collected essay and a second edition of his magnum opus Natural Law and Natural Rights, and in 2013 a major Festschrift in his honour. Finnis was appointed Queen’s Counsel (honoris causa) in 2017.
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