¹ R. (on the application of Miller and another) v Secretary of State for Exiting the European Union [2017] UKSC 5.

² I make no assumption that the understandings within the English and Welsh, the Scots and the Northern Irish legal communities are identical.

³ MacCormick, D.N. and Summers, R.S., Interpreting Precedents: A Comparative Study (Aldershot 1997), ch. 4Google Scholar; Bell, J., Boyron, S. and Whittaker, S., Principles of French Law, 2nd ed. (Oxford 2008), 25–32 Google Scholar. For a critique, see especially de S.-O.-L'E. Lasser, M., Judicial Deliberations: A Comparative Analysis of Judicial Transparency and Legitimacy (Oxford 2004)Google Scholar. German discussions typically refer to Article 20 III GG before acknowledging the reality that cases are a legitimate authority in legal argumentation: see MacCormick and Summers, Interpreting Precedents, ch. 2.

⁴ von Savigny, F.C., System des heutigen Römischen Rechts, vol. 6 (Berlin 1840–48), 11–13 Google Scholar.

⁵ Dalloz, , Code Civil annoté 2017 (Paris 2016), 1494–1500 Google Scholar.

⁶ European Ombudsman, European Code of Good Administrative Behaviour, Article 18(1): Every decision of the institution which may adversely affect the rights or interests of a private person shall state the grounds on which it is based by indicating clearly the relevant facts and the legal basis of the decision. <https://www.ombudsman.europa.eu/en/resources/code.faces#/page/15 > (accessed 23 January 2018).

⁷ See e.g. McBride, N.J., Letters to a Law Student, 3rd ed. (London 2014), Part 3Google Scholar.

⁸ Pizzorusso, A., Law in the Making: A Comparative Study (Berlin 1988), 18 CrossRefGoogle Scholar.

⁹ Raz, J., The Authority of Law (Oxford 1979), 47–48 Google Scholar.

¹⁰ For this essay, nothing turns on whether one considers this interpretation process as a positivist or any other kind of activity.

¹¹ R. Sacco, “Legal Formants” (1991) 39 Am.J.Comp.L. 1, at 21–23.

¹² Fikentscher, W., Methoden des Rechts, vol. IV (Tübingen 1977), 299–301 Google Scholar. He distinguished the words of a text, their meaning in ordinary language, and their legal significance. Though one may be able to treat the wording as fixed, the legal significance is a matter of interpretation and the Fallnorm (the rule to be applied in the case) is only the product of that reasoning process.

¹³ See Bell, J. and Engle, G., Cross on Statutory Interpretation, 3rd ed. (London 1995), 38–43 Google Scholar.

¹⁴ Allan, T.R.S., The Sovereignty of Law (Oxford 2013), 49 Google Scholar.

¹⁵ French Constitution, Article 13.

¹⁶ Declaration of the Rights of Man and of the Citizen, Article 13.

¹⁷ See Dashwood, A. et al. (eds.), Wyatt and Dashwood's European Union Law, 6th ed. (Oxford 2011), 322–24Google Scholar.

¹⁸ Preamble to the French Constitution of 1946, para. 12.

¹⁹ It might be objected that “values” could not be directly applied as sources of law. But they are often used directly to qualify or limit the scope of legal rules or to object to decisions that have been made by public bodies: see further J. Bell, “External Dimensions of the French Constitution” (2017–8) 57 Virginia International Law Journal (forthcoming).

²⁰ Summers, R.S., Form and Function in a Legal System (Cambridge 2006), 42–47 Google Scholar; also Bankowski, Z., Living Lawfully (Dordrecht 2001), ch. 7Google Scholar.

²¹ See Article 3(2) of the Law of 5 July 1985.

²² Peczenik, A., On Law and Reason (Dordrecht 1989), 318 CrossRefGoogle Scholar.

²³ Ibid., at pp. 319–21.

²⁴ Ost, F. and Van de Kerchove, M., De la pyramide au réseau? Pour une théorie dialectique du droit (Brussels 2002), 352–55Google Scholar.

²⁵ Ibid, at p. 326. See also, and very importantly, Simmonds, N., The Idea of Law (Oxford 2007), 123ffGoogle Scholar.

²⁶ Ibid, at pp. 328–29.

²⁷ Ibid., at p. 337.

²⁸ Ibid., at pp. 339–40.

²⁹ Ibid, at p. 354.

³⁰ Hart, H.L.A., The Concept of Law, 3rd ed. (Oxford 2012), 293 Google Scholar.

³¹ E.g. Bell, J., in Burrows, A. (ed.), English Private Law, 3rd ed. (Oxford 2013), ch. 1Google Scholar.

³² Pizzorusso, A., Fonti del diritto: Art. 1–9 (Bologna 1977), ch. 1Google Scholar.

³³ Ibid., at pp. 11–12.

³⁴ Ibid., at p. 27, note 4.

³⁵ “Rules are conventional social practices if the general conformity of a group to them is part of the reasons which its individual members have for acceptance; by contrast merely concurrent practices such as the shared morality of a group are constituted not by convention but by the fact that members of the group have and generally act on the same but independent reasons for behaving in certain specific ways” (Hart, Concept of Law, p. 256).

³⁶ Peczenik, On Law and Reason, p. 324.

³⁷ More correctly, we probably have to look at what the influential members of the legal community do: see Paterson, A., The Law Lords (London 1982)CrossRefGoogle Scholar on who influences the Law Lords; Paterson, A., Final Judgment (Oxford 2013), ch. 6Google Scholar. A similar analysis is made in France: see Le Berre, H., Les revirements de jurisprudence en droit administratif de l'an VIII à 1998 (Paris 1999), 475–502 Google Scholar.

³⁸ Pizzorusso, Fonti del diritto, pp. 174–75.

³⁹ See Ost and Van de Kerchove, De la pyramide au réseau, pp. 65–77.

⁴⁰ Vogenauer, S., “Sources of Law and Legal Method” in Reimann, M. and Zimmermann, R. (eds.), The Oxford Handbook of Comparative Law (Oxford 2006), 885 Google Scholar.

⁴¹ Hart, Concept of Law, pp. 94–110.

⁴² Alexy, R., A Theory of Legal Argumentation (Oxford 1989), 214, 218Google Scholar. Also Simmonds, The Idea of Law, p. 136: “… the judgment must demonstrate or tacitly assume that the application of [legal] rules was itself proper and justifiable from the perspective of values that the litigants ought themselves to accept and endorse.”

⁴³ The most famous exception is article 1 of the Swiss civil code: “If no command can be taken from the statute, then the judge shall pronounce in accordance with the customary law, and failing that, according to the rule which he as a legislator would adopt. He should be guided therein by approved precept and tradition.”

⁴⁴ Peczenik, On Law and Reason, p. 322. Substantive reasons can more easily displace “may” or “should” reasons than “must-source” reasons.

⁴⁵ Hart, Concept of Law, p. 94.

⁴⁶ Ibid, at pp. 100–01.

⁴⁷ Ibid., at p. 294 (an original note on the topic of sources, mainly focused on the work of Salmond and C.K. Allen).

⁴⁸ Ibid., at pp. 81–82.

⁴⁹ E.g. the importance of contemporaneous exposition in the interpretation of statutes: Bell and Engle, Cross on Statutory Interpretation, p. 147.

⁵⁰ See note 5 above.

⁵¹ Cornish, W. et al. , Oxford History of the Laws of England, vol. XI: 1820–1914 English Legal System (Oxford 2010), 70 Google Scholar.

⁵² Hart, Concept of Law, p. 115.

⁵³ Ibid., at pp. 98–99.

⁵⁴ Simpson, A.W.B., “The Common Law and Legal Theory” in Simpson, A.W.B. (ed.), Oxford Essays in Jurisprudence (Second Series) (Oxford 1973), 94–95 Google Scholar.

⁵⁵ Le Berre, Les revirements de jurisprudence, pp. 475–502.

⁵⁶ Rorive, I., Le revirement de jurisprudence: Etude de droit anglais et de droit belge (Brussels 2003), 489, 506–08Google Scholar.

⁵⁷ Pizzorusso, Fonti, p. 542.

⁵⁸ Ibid.

⁵⁹ Ibid., at p. 546.

⁶⁰ Ibid., at p. 545.

⁶¹ See Kiwanuka, R., “On Revolution and Legality in Fiji” (1988) 37 I.C.L.Q. 961, at 968–73Google Scholar. J. M. Eekelaar, “Principles of Revolutionary Legality”, in Simpson, Oxford Essays in Jurisprudence, pp. 22–23.

⁶² Case 26/62, Van Gend en Loos [1963] E.C.R. 1.

⁶³ Case 106/77, Amministrazione delle Finanze dello Stato v Simmenthal (no.2) [1978] E.C.R. 629.

⁶⁴ Corte cost. 30 October 1975 n. 232, Frontini, Foro Italiano 1975.I.2661. Also Italian judges cannot disapply incompatible Italian rules without referring the matter to the Corte costituzionale: Corte. Cost. 28 July 1976 n. 205: see Pizzorusso, Fonti, pp. 491–92, note 14.

⁶⁵ Corte cost. 8 June 1984 n. 170, Granital v Ministero delle Finanze, Foro Italiano 1984.I.2062.

⁶⁶ Ibid., columns 2075–2076.

⁶⁷ Corte cost. 23 April 1985 n. 130, BECA S.p.A. e altri v Amministrazione finanziaria dello Stato.

⁶⁸ Corte cost. 13 July 2007 n. 284, <http://www.giurcost.org/decisioni/2007/0284s-07.html> (accessed 21 December 2017). The reporter judge in this case was Tesauro, a former Advocate General at the Luxembourg court.

⁶⁹ “Ora, nel sistema dei rapporti tra ordinamento interno e ordinamento comunitario, quale risulta dalla giurisprudenza di questa Corte, consolidatasi, in forza dell'art. 11 della Costituzione, soprattutto a partire dalla sentenza n. 170 del 1984, le norme comunitarie provviste di efficacia diretta precludono al giudice comune l'applicazione di contrastanti disposizioni del diritto interno, quando egli non abbia dubbi – come si è verificato nella specie – in ordine all'esistenza del conflitto. La non applicazione [del diritto interno] deve essere evitata solo quando venga in rilievo il limite, sindacabile unicamente da questa Corte, del rispetto dei principi fondamentali dell'ordinamento costituzionale e dei diritti inalienabili della persona.”

⁷⁰ Above p. 48.

⁷¹ BVerfGE 37, 271. See Solange II, BVerfGE 73, 339; BVerfGE 89, 155 (Maastricht); BVerfGE 123, 267 (Lisbon Treaty); BVerfGE 132, 195 (European Stability Mechanism); BVerfGE 135, 317 (ESM Treaty). Decision of Second Senate, 21 June 2016, 2 BvR 2728/13 (European Central Bank).

⁷² See BVerfGE 22, 293, p. 296 (8 October 1967). Scholz, R., Maunz-Dürig Grundgesetz (Tübingen 2009), Article 23, §19Google Scholar; Currie, D., The Constitution of the Federal Republic of Germany (Chicago 1994), 94–98 Google Scholar.

⁷³ See BVerfGE 31, 145 (173–174) (Milk Powder, 9 June 1971).

⁷⁴ CE 1 March 1968, Semoules de France, no. 62814, conclusions Questiaux, commented on perceptively by Wade in (1972) 88 L.Q.R. 1. Also CE Ass. 22 décembre 1978, Ministre de l'Intérieur c/ Cohn-Bendit, Leb. 524, conclusions Genevois. Brown, L.N. and Bell, J., French Administrative Law, 5th ed. (Oxford 1998), 283–86Google Scholar.

⁷⁵ Cass. Ch. Mixte, Société des cafés Jacques Vabre D. 1975, 497 conclusions Touffait.

⁷⁶ CC 21 octobre 1988, Ass. Nat. Val d'Oise 5^e circ. Rec. 183 ; RFDA 1988, 908 note Genevois ; Boyron, S., The Constitution of France (Oxford 2013), 219–29Google Scholar.

⁷⁷ CE Ass. 20 October 1989, Leb. 190 conclusions Frydman; RFDA 1989, 824 note Genevois.

⁷⁸ CC Décision n° 2004–505 DC, 19 November 2004, para. 7; Bell, J., “French Constitutional Council and European Law” (2005) 54 I.C.L.Q. 735 Google Scholar.

⁷⁹ See the views of Terré, F., Introduction générale du droit, 5th ed. (Paris 2000), 218 Google Scholar: “Procédant de choix idéologiques favorables à l'internationalisation et à l'européanisation de notre droit … les solutions adoptées par la Cour de cassation et le Conseil d'Etat entraînent l'intégration dans notre ordre juridique … d'une énorme mass sécrétée, au jour le jour par la bureaucratie bruxelloise.”

⁸⁰ See the arguments of Procureur général Ganshof van der Meersch in Le Ski, Pas. 1971.I at 898–99: “une évolution jurisprudentielle est meilleure qu'un changement de Constitution.”

⁸¹ Professor Finnis cautioned that the “conduit pipe” analogy was inadequate: “Brexit and the Balance of our Constitution”, Sir Thomas More lecture, 1 December 2016, p. 20.

⁸² M. Elliott, “The Supreme Court's Judgment in Miller: In Search of Constitutional Principle” [2017] C.L.J. 257, at 272. Also D. Feldman, “Pulling a Trigger or Starting a Journey? Brexit in the Supreme Court” [2017] C.L.J. 217.

⁸³ The view in Belgium had already changed during the course of 1971 in Cass. 27 mai 1971, S.A. Fromagerie Franco-Suisse “Le Ski” c. Ministère des affaire Économiques, Pas 1971, 886.

⁸⁴ Elliott argues that this view is the only one to make sense after rejecting the view that the rule of recognition has changed: Elliott, “The Supreme Court's Judgment in Miller”, pp. 272–73.

⁸⁵ Bradley, A.W.B., “The Sovereignty of Parliament – in Perpetuity?” in Jowell, J. and Oliver, D. (eds.), The Changing Constitution (Oxford 1985), 39 Google Scholar.

⁸⁶ Mitchell, J.D.B., “What Happened to the Constitution on 1^st January 1973?” (1980) 11 Cambrian L.Rev. 69, at 81–82Google Scholar.

⁸⁷ Wade, H.W.R., “What Has Happened to the Sovereignty of Parliament?” (1991) 107 L.Q.R. 1, at 4Google Scholar; and Wade, H.W.R., “Sovereignty – Revolution or Evolution?” (1996) 112 L.Q.R. 568 Google Scholar; cf. Craig, P.P., “Sovereignty of the UK Parliament after Factortame” (1991) 11 Y.B.E.L. 221 Google Scholar. Wade had already expressed a similar view just before the entry of the UK into the EEC: “In a country which has no overriding constitutional legislation, a change in this Grundnorm can be achieved only by a legal revolution and only if the judges elected to abandon their deeply rooted allegiance to the ruling Parliament of the day”: Wade, H.W.R., “Sovereignty and the European Communities” (1972) 88 L.Q.R. 1, at 5Google Scholar. By contrast Allan argues that no significant change or recognition of change in sources took place in Lord Bridge's speech: Allan, Sovereignty of Law, pp. 148, 150.

⁸⁸ Wade, “Sovereignty – Revolution or Evolution?”, p. 574.

⁸⁹ Wade, “Sovereignty and the European Communities”, pp. 4–5.

⁹⁰ See Lords Neuberger and Mance, HS2 [2014] UKSC 3, at [206].

⁹¹ R. (on the application of HS2 Action Alliance Limited) v The Secretary of State for Transport and another [2014] UKSC 3, at [79]; see also Lords Neuberger and Mance at [206]–[208]. I am grateful to Trevor Allan for this point. See also Elliott, “The Supreme Court's Judgment in Miller”, p. 269.

⁹² Allison, J., The English Historical Constitution (Cambridge 2007), 115 CrossRefGoogle Scholar.

⁹³ Ibid., at pp. 116–19, 125–26.

⁹⁴ Allan, T.R.S., Law, Liberty, and Justice: The Legal Foundations of British Constitutionalism (Oxford 1993), 280 Google Scholar. This fits with his idea that the UK has a common law constitution: ibid., at p. 4; and Allan, T.R.S., The Sovereignty of Law (Oxford 2013), 3 Google Scholar. His earlier work on the status of European law reflects this approach and counters the perspective of Wade: see note 95 below.

⁹⁵ Allan, T.R.S., “Parliamentary Sovereignty: Lord Denning's Dexterous Revolution” (1983) 3 O.J.L.S. 22 Google Scholar.

⁹⁶ See Schwarze, J., Birth of a European Constitutional Order (Baden-Baden 2001), 511–16Google Scholar.

⁹⁷ Granital, note 65 above, Foro Italiano 1984. I. 2062 at cols.2075–2076.

⁹⁸ See e.g. BGHZ 29, 65, Stromkabel (9 December 1958).

⁹⁹ Hart, Concept of Law, p. 256.

¹⁰⁰ See in particular Blom-Cooper, L., “1966 and All That: The Story of the Practice Statement” in Blom-Cooper, L., Dickson, B. and Drewry, G. (eds.), The Judicial House of Lords 1876–2009 (Oxford 2009), ch. 9Google Scholar; and Paterson, The Law Lords, pp. 146–53.

¹⁰¹ Practice Statement (Judicial Precedent) [1966] 3 All E.R. 77.

¹⁰² (1861) 9 H.L.C. 274.

¹⁰³ [1898] A.C. 375.

¹⁰⁴ Salmond, J.W., Jurisprudence, 11th ed. (London 1957), 187–88Google Scholar.

¹⁰⁵ Cross, R., “The House of Lords and the Rules of Precedent” in Hacker, P.M. and Raz, J. (eds.), Law Morality and Society (Oxford 1977), 156–57Google Scholar.

¹⁰⁶ Harris, J.W., Cross and Harris on Precedent, 4th ed. (Oxford 1991), 104–08, especially 105Google Scholar.

¹⁰⁷ P.J. Evans, “The Status of Rules of Precedent” [1982] C.L.J. 162, at 165–66.

¹⁰⁸ Harris, Cross and Harris on Precedent, p. 106.

¹⁰⁹ Blackshield, A., “‘Practical Reason’ and ‘Conventional Wisdom’, in the House of Lords and Precedent” in Goldstein, L. (ed.), Precedent in Law (Oxford 1987), ch. 5, esp. 109–31Google Scholar.

¹¹⁰ Knuller v D.P.P. [1973] A.C. 435, 485.

¹¹¹ Blackshield, “‘Practical Reason’ and ‘Conventional Wisdom’”, pp. 131–51. His view on the impossibility of conventions being changed by a single act is contestable: see for example the Sewel Convention.

¹¹² Ibid, at p. 152.

¹¹³ Simpson, A.W.B., “The Ratio Decidendi of a Case and the Doctrine of Binding Precedent”, in Guest, A. (ed.), Oxford Essays in Jurisprudence, 1st series (Oxford 1961), 154–55Google Scholar.

¹¹⁴ Evans, “The Status of Rules of Precedent”.

¹¹⁵ Duxbury, N., The Nature and Authority of Precedent (Cambridge 2008), 129–39Google Scholar.

¹¹⁶ Ibid., at p. 135.

¹¹⁷ Ibid., at p. 136.

¹¹⁸ Ibid., at pp. 139–49; Harris, Cross and Harris on Precedent, pp. 107–08.

¹¹⁹ See the current draft of clause 6(4) of the European Union (Withdrawal) Bill.

¹²⁰ Fitzgerald, P.J., Salmond on Jurisprudence, 12th ed. (London 1966), 160 Google Scholar.

¹²¹ See Harris, Cross and Harris on Precedent, pp. 99, 148–52.

¹²² Ibid., at p. 99; MacCormick and Summers, Interpreting Precedents, p. 38.

¹²³ Evans, “The Status of Rules of Precedent”, pp. 173, 178.

¹²⁴ Paterson, The Law Lords, pp. 147–48; Stevens, R., Law and Politics: The House of Lords as a Judicial Body, 1800–1976 (London 1979), 432, 464–67, 470–73, 496–502, 528–29Google Scholar.

¹²⁵ Paterson, The Law Lords, p. 149.

¹²⁶ Evans, “The Status of Rules of Precedent”, p. 172.

¹²⁷ See Raz, The Authority of Law, pp. 185–86; Duxbury, The Nature and Authority of Precedent, pp. 113–16.

¹²⁸ Baker, J.H., The Law's Two Bodies: Some Evidential Problems in English Legal History (Oxford 2001), 78 Google Scholar. On the role of scholarship and tradition in providing the coherence and sense to otherwise oblique statutory rules or judicial pronouncements, see Baker, J.H., The Common Law Tradition: Lawyers, Books and the Law (London 2000), 25 Google Scholar.