Case Facts
The claimant, Albert Raymond Blackburn, brought two actions against the Attorney-General seeking declarations that the United Kingdom government's proposed signature of the Treaty of Rome would be unlawful. His argument was that by signing the treaty, the government would be surrendering in part the sovereignty of the Crown in Parliament — and that such a surrender would be permanent and irreversible.
At the time of the hearing before the Court of Appeal, no agreement had yet been reached to sign the treaty. Nevertheless, it was accepted by the court that, were the treaty to be signed, the step would indeed be irreversible and would limit the sovereignty of the United Kingdom. The court assumed that upon signing, many regulations made by the European Economic Community would automatically become binding on the United Kingdom, and that the courts would be required to follow decisions of the European Court in certain defined respects, including the construction of the treaty. Lord Denning MR conceded that Mr Blackburn was "quite correct" that signing the Treaty of Rome would be an irreversible step, and that the sovereignty of these islands would thenceforward be limited and shared with others.
In support of his argument on parliamentary sovereignty, Mr Blackburn cited Professor Maitland's Constitutional History of England for the proposition that "We have no irrepealable laws; all laws may be repealed by the ordinary legislature, even the conditions under which the English and Scottish Parliaments agreed to merge themselves in the Parliament of Great Britain." The Attorney-General contended, in response, that the treaty-making power was an exercise of Crown prerogative, entirely beyond the supervisory jurisdiction of the courts.
The two actions had originally been struck out by Eveleigh J on 27 February 1971 under RSC Ord 18, r 19 and the inherent jurisdiction of the court, on the ground that they disclosed no reasonable cause of action and were vexatious and an abuse of process. Mr Blackburn appealed in person to the Court of Appeal.
Held
The Court of Appeal dismissed the appeals on two distinct grounds.
First, the court held that the treaty-making power of this country rests not in the courts, but in the Crown — that is, Her Majesty acting on the advice of her Ministers. When Ministers negotiate and sign a treaty, even one of such paramount importance as the Treaty of Rome, they act on behalf of the country as a whole and exercise the prerogative of the Crown. Their action in so doing cannot be challenged or questioned in the courts. In this regard, Lord Denning MR cited Rustomjee v R (1876) for the principle that the Crown, in making and performing a treaty, acts in her sovereign character, is beyond the control of municipal law, and her acts are not to be examined in her own courts. The court further noted that it takes no notice of treaties as such until they are embodied in laws enacted by Parliament, and then only to the extent that Parliament directs.
Second, the court declined to pronounce upon the question whether, if Parliament were to pass an Act implementing the Treaty of Rome — which, once signed, would be irrevocable — a subsequent Parliament could reverse that enactment. The court considered that this question should not be pronounced upon until such time as the event actually happened. Since no implementing legislation yet existed, and indeed no treaty had yet been signed, the question was entirely hypothetical and unsuitable for judicial determination by way of declaration.
Ratio Decidendi
The ratio decidendi rests upon two distinct pillars, each of which independently justified the dismissal of the appeals.
The first pillar is that the prerogative power to negotiate and conclude treaties is vested exclusively in the Crown and is not subject to review by the courts. No cause of action capable of supporting a declaration could arise from the prospective exercise of this prerogative power.
The second pillar is that the court ought not to make declarations concerning the powers of Parliament — and in particular, concerning whether a future Parliament could repeal legislation implementing the Treaty of Rome — where the circumstances said to call for judicial intervention are entirely hypothetical. No implementing statute existed at the time of the proceedings. Salmon LJ reasoned that the sole function of the courts is to decide and enforce what the law is, not what it should be now or in the future. Stamp LJ reasoned that it is no part of the court's function to make declarations in general terms regarding the powers of Parliament, particularly in circumstances that are hypothetical. Together, these distinct lines of reasoning form the ratio on the second ground.
Obiter Dicta
Lord Denning MR made several observations that, while not strictly necessary to the disposal of the appeals, are of considerable constitutional significance.
His Lordship acknowledged that signing the Treaty of Rome would represent an irreversible step, accepting Mr Blackburn's submission on that point. He observed that it would be a historic moment for this country, but emphasised that the legal question of whether a future Parliament could repeal implementing legislation was not one the courts could or should answer in advance.
Lord Denning MR further reflected upon the principle that no Parliament can bind its successors — a principle well established in constitutional theory and cited by Mr Blackburn from Professor Maitland's Constitutional History of England. His Lordship noted that, although this principle has always been asserted in the textbooks, it might be that circumstances could arise in which Parliament's freedom was as a practical matter constrained by treaty obligations of a far-reaching character. However, he made clear that this was a matter for Parliament and not for the courts to resolve prospectively.
These observations on the relationship between treaty obligations, the sovereignty of Parliament, and the limits of judicial competence to pronounce on future constitutional arrangements proved prescient in light of subsequent litigation, including Factortame (No 2) [1991] and R (Miller and another) v Secretary of State for Exiting the European Union [2017], both of which required the courts to grapple directly with the interaction between parliamentary sovereignty and European Union law. The present case established that such questions could not be resolved pre-emptively in the abstract, but only when the relevant legislative and constitutional facts had actually materialised.