In The Social Contract, Jean-Jacques Rousseau wrote that the people of England are “sorely mistaken” for considering themselves to be free. They are only free at the moment of the election of members of parliament. After this, they become “enslaved”; they are “nothing”.
The most fundamental rule of UK Constitutional law is that what the Queen-in-Parliament enacts is law. This means that Parliament has the right to make or unmake any law; no person or body has the right to override or set aside the legislation of parliament. There are two important corollaries to be taken from this. The first is that legislation enacted by Parliament cannot be subjected to displacement by the executive. The decision of the High Court of England in R (Miller) v Secretary of State for exiting the EU  EWHC 2768 (hereinafter, Miller) turned on this principle. The second corollary is that the validity of a statute cannot be questioned “on the ground of its having been passed or kept alive in opposition to the will of electors”.  The importance of this will be examined below.
Miller involved a challenge to the UK government’s attempt to give notice of the UK’s decision to leave the EU under Article 50 of the Treaty of Lisbon by the exercise of the Crown’s prerogative powers and without reference to Parliament. The Crown is provided with legal powers by two sources: statute and the prerogative. The latter is described by Dicey as “the residue of discretionary or arbitrary power which at any given time is legally left in the hands of the Crown.” The power to grant passports or enter into international treaties are prerogative powers which the Crown enjoys alone.
For the challenge in Miller to be successful therefore, it had to be demonstrated that the government does not have legal authority to trigger Article 50 and leave the EU. The court’s task was to uphold the rule of law in the UK. At its simplest, the rule of law provides that “the executive may do nothing without clear legal authority first permitting its actions”. It is therefore important that for the rule of law to be effective the courts must be able and willing to police the boundaries of the executive’s statutory authority and to ensure that the government does not misuse or abuse its prerogative power.
The High Court duly ruled that the government did not have legal authority for such an action. Triggering Article 50 would involve a change to the domestic law, as it would involve a repeal of the European Communities Act 1972 which had been passed at the time of entry into the EU. EU law granted UK citizens with numerous rights, which, the court held, it was not within the power of the executive to take away. Counsel for the Secretary of State argued that the executive had a prerogative power to enter into international treaties, and that nothing had been done in the 1972 Act to remove this power. However, this was rejected by the court as there was a direct link between the entering into an international treaty and the change this would effect on domestic law. Further, the 1972 Act had become a constitutional statute, making it especially unlikely that Parliament intended that their continued existence should be left up to the executive.
Importantly, the High Court in Miller drew from case-law which determined that the prerogative power was really “a relic of a past age (…) only available for a case not covered by statute”. Thus, once an area is governed by statute, it is not possible for the executive to intervene and use the prerogative power to govern in that area. This is a logical consequence of the fact that legislation is supreme and cannot be subject to displacement by the executive.
One of the implications of the rule of Parliamentary Sovereignty which becomes clear after the decision in Miller and in light of the current political reality in the UK, is that it is not beyond the realm of possibility for Parliament to enact a law which is opposed to the will of the people. This is because, as Dicey put it, as a matter of law, the judges know nothing about any such will, except as expressed in legislation, and cannot therefore question the validity of legislation on such grounds. Perhaps this is why Rousseau felt that the English people were not properly free.
Dicey would argue that Parliament is subject to political control, and if Parliament does something the people don’t want, the people will vote for new representatives at the next election. However, what if, in the intervening period, Parliament voted to leave the EU, repealing the 1972 Act? And what if this was contrary to the will of the people? Surely, by the time of the next election, there wouldn’t be much use in “voting out” your MP who voted to leave the EU. It would be too late by that stage. You’d be out of the EU. You’d start to think that maybe Rousseau was right after all.
The people of the UK voted to leave the EU last June by a majority of 52%. What if, in light of the new life given to the concept of Parliamentary Sovereignty in the UK, Parliament were to “block Brexit”? The pound soars, Donald Trump resigns and pigs fly. But aside from all that, Parliament would have committed a legislative act (by voting not to repeal the 1972 Act) which was clearly contrary to the will of the people. Isn’t there any way a citizen of the UK could challenge this legislative act through the courts, the way Gina Miller did?
The rule that what the Queen-in-Parliament enacts is law is a common law rule. It consists in judicial recognition of political reality. Should the political reality change, there is nothing stopping the common law changing with it. Thus, shortly after the UK entered the EU, a case came before the courts in England which involved a conflict between a UK statute (the Merchant Shipping Act 1988) and European law. After a referral to the ECJ, the House of Lords held that the 1988 Act was incompatible with the requirements of EU law and suspended its operation. The local courts recognised this shift in legislative authority, as they possessed “a political capacity to alter the fundamental rule of the British constitution”. Some argue that this case should be read as Parliament simply placing limits on itself in the 1972 Act, which applied in the 1988 Act. After all, Parliament entered the European Community aware of the constraints that came with membership. Regardless, the consequence of the decision was that it was no longer the case that “Whatever the Queen-in-Parliament enacts is law”.
Suppose the Parliament were to enact a law that ordered the killing of all blue-eyed babies. Such a statute would, under the rule that “whatever the Queen-in-Parliament enacts is law”, be a valid law. However, the practice of the UK courts of accepting as a rule that “whatever the Queen-in-Parliament enacts is law” has been built up around statutes that have been nowhere near as outrageous as this. So, all the practice of the UK courts allows us to say is that they accept as a rule that whatever the Queen in Parliament enacts is law, so long as the Queen in Parliament continues to enact statutes that are not so morally outrageous.
If Parliament were to enact such a morally outrageous statute as this, all bets would be off as to what the courts would do. If the courts refused to recognise it as a valid statute, then we could say that the rule that “whatever the Queen in Parliament enacts is law” would have developed so that now we would be able to say that “whatever the Queen in Parliament enacts is law, unless the Parliament enacts a morally outrageous law like this one”. If, on the other hand, the courts did recognise it as a valid statute, then equally we would be able to say that the rule employed by the courts that “whatever the Queen in Parliament enacts is law” would have developed so that now it would be true to say that “whatever the Queen in Parliament enacts is law”.
Thus, there is nothing in theory stopping the courts from developing the rule “whatever the Queen-in-Parliament enacts is law” whether in reaction to the current political reality or otherwise. So, if Parliament were to “block Brexit” it would be impossible to predict whether an individual would be successful in an attempt to challenge the validity of the European Communities Act 1972 or of any other legislation passed by Parliament which sought to keep the UK within in the EU. There would be nothing stopping the courts from refusing to recognise it as valid law, given that until now, the courts have only recognised the rule that whatever Parliament enacts is law where there has not been a clear indication that the people of the UK do not want such a law. Dicey’s objection (that judges know nothing about any will of the people, except as expressed in legislation) does not reflect the current political reality.
Of course, in reality, all that Parliament will do is control the government’s triggering of Article 50 so that Brexit is achieved on terms which are agreeable to it. It won’t block Brexit. But the decision in Miller comes as an important reminder that “Parliament is the institution through which the government must govern, and it is the first responsibility of the government to ensure that it continues to enjoy Parliamentary support, for in English public law no government can operate without it.” It also reminds us that it is not beyond the capacity of the courts to develop the most fundamental rule in UK Constitutional law, in reaction to political reality. All bets are off as to whether the Parliament must exercise its authority through the people.
 Rousseau, Du Contrat Social, Livre III, Chp. 15.
 R (Miller) v Secretary of State for exiting the EU  EWHC 2768.
 AV Dicey, Introduction to the Study of Law and the Constitution (1915) 57.
 Attorney General v De Keyser’s Royal Hotel  AC 508.
 Adam Tomkins, Public Law (Oxford University Press 2003) 78.
 Ibid 81.
 Burmah Oil Co (Burman Trading) Ltd v Lord Advocate  AC 75.
 Dicey (n 5) 71.
 Tomkins (n 7).
 R v Secretary of State for Transport, ex parte Factortame (No 2)  AC 658.
 Nicholas Barber, The Constitutional State (Oxford University Press 2010) 116.
 Paul Craig, ‘The Sovereignty of the UK Parliament after Factortame’ (1991) 11 (1) Yearbook of European Law 252.
 N. W. Barber, ‘The Afterlife of Parliamentary Sovereignty’ (2011) 9 International Journal of Constitutional Law 144.
 Leslie Stephen, Science of Ethics, 1st ed (1882) 137.
 Nicholas McBride and Sandy Steel, Great Debates in Jurisprudence (Palgrave 2014) 46.
 Tomkins (n 7) 91.