Robert Craig: The Abeyance Principle and the Frustration Principle

Robert CraigIntroduction

I have argued on this blog and in the Modern Law Review (MLR) (forthcoming, November edition – copies available on request on the usual terms: that the power to trigger Article 50 should be seen as a statutory power under s 2(1) of the European Communities Act (‘ECA’) – the ‘statutory basis’ claim. This claim has recently received heavyweight support from Keith Ewing on this blog. The idea of statutory authorisation was also explicitly suggested to Counsel in oral argument by the Lord Chief Justice but the point was not taken up by the Government (Day 3: p119-20).

However, my MLR article also draws a novel distinction that is quite separate from the ‘statutory basis’ claim. It will be suggested in this post that this distinction is essential for a clear understanding of the relationship between statute and prerogative and it is worth spelling out the point independently. This post is necessarily briefer than I would wish – a fuller explanation can be found in the MLR piece. It is submitted that some potential confusion in academic commentary and the High Court decision in Miller may be dispelled if the analytical distinction in the law suggested here is accepted.

This post argues that two principles that ought to be kept analytically separate are being conflated. The first principle could be labelled ‘the abeyance principle’. It means that where statute and prerogative directly overlap, the prerogative goes into abeyance. Essentially, the statute replaces the previous prerogative power, which disappears from the scene and can no longer be used. The second principle is ‘the frustration principle’. It means that where a statute and prerogative could be inconsistent, without overlapping, the prerogative cannot be used inconsistently with the intention of parliament as expressed in the relevant statute. The crucial distinction is that in the first category, the prerogative is no longer available to the Crown at all. In the second category, the prerogative is still ‘live’ and available to the Crown – it simply may not be exercised in a way that is inconsistent with parliament’s intention. It is important to note that all factual scenarios fall either under the abeyance principle or the frustration principle. It is ‘either/or’ not ‘both/and’. A bright line distinction between the two areas of law should be maintained.

Before turning to the analysis of how this distinction plays out in the case law and Miller itself, it is necessary to draw attention to three categories of rights that were set out in Miller. These need to be explained as they are referred to on a number of occasions later in this post.

Category 1 rights are ones that are within the control of parliament to replace. A good example is rights under the Working Time Directive which parliament could simply re-enact.

Category 2 rights are ones that could only be salvaged with the agreement of third party states. A good example is freedom of movement.

Category 3 rights are ones that will inevitably be lost. A good example is the right to vote for a Member of the European Parliament (MEP) under the European Parliamentary Elections Act 2002 (‘the 2002 Act’)

It would be fair to say that the general expectation amongst those observing the hearing was that if the claimants were going to win, the most likely basis was the Category 3 rights argument. This was because (as I explain below), the Government appeared to have no answer to this point. As it happened, the court went much further and the Government comprehensively lost on all three categories. This should not obscure the fact that the argument over Category 3 rights was viewed as the strongest, was treated as such by Counsel for the claimants and remains by far the strongest argument for the claimants even now.

The central claim of this post is that the case as presented by the Government in the High Court falls squarely under the frustration principle.

The abeyance principle

The paradigm example of the abeyance principle can be seen in De Keyser’s Hotel. In that case, a statutory framework was imposed by parliament that abrogated whatever prerogative power there might have been (although that was a matter of some controversy in itself). Lord Parmoor said:

When the power of the Executive…has been placed under Parliamentary control, and directly regulated by statute, the Executive no longer derives its authority from the Royal Prerogative of the Crown but from Parliament.

It is clear from this case, therefore, that when the abeyance principle applies, the Crown cannot exercise the prerogative at all because parliament has occupied the ground either explicitly or by necessary implication. A recent clear example is the Fixed-term Parliaments Act 2011, which sets out a comprehensive statutory code whereby Parliament may be dissolved early and plainly excludes any further use of the former prerogative of dissolution, which therefore goes into abeyance (some would say is abolished).

The frustration principle

One of the most powerful cases illustrating the frustration principle is Laker Airways. In that case, the exercise of the prerogative inevitably frustrated the exercise of domestic landing rights of Laker Airways granted by Act of Parliament. The President was asked by the UK Government to revoke the landing rights for Laker Airways in the USA. There was no direct overlap between the domestic statute and the prerogative. The Court of Appeal held that the Executive had ‘by a side wind… deprived [Laker Airways] of the protection which the statute affords them’. The Crown had therefore frustrated the will of parliament which had wanted to promote competition in that market and had removed procedural rights possessed by Laker Airways under the Civil Aviation Act.

Some might argue that Laker is a stronger factual matrix than Miller because the company went bankrupt immediately when the prerogative was exercised. However, it could well be argued that Miller is stronger because whilst the domestic statutory landing rights in Laker could in theory still have been exercised – perhaps to an alternative destination – the Category 3 right to vote or stand in European Elections (to take just one example) will definitely be lost. There is no prospect whatsoever of European elections being held if the Article 50 trigger inexorably leads to exit – as conceded by the Government.

In terms of the abeyance principle, it is nowhere suggested that the relevant domestic Act in Laker explicitly or by necessary implication occupied the ground where the prerogative was located. The prerogative was not abrogated. Yet the claimants won. They won because Laker is authority for the proposition that you cannot use the prerogative to frustrate the intention of parliament even if it does not overlap or place into abeyance the prerogative power. The Crown retained, and still retains, the relevant prerogative of negotiating treaties like the one in Laker. This case is therefore a clear case of the application of the frustration principle.

Another case providing powerful support for the claimants is Fire Brigades Union (‘FBU’). In that case, a statutory provision (Criminal Justice Act 1988 ‘(CJA’) – s 171) was in force and prevented the Crown from implementing a prerogative scheme of ex gratia payments. The in force section did not overlap or occupy the ground or abrogate the prerogative in any way. The statutory payment scheme set out in the CJA (ss 108-117) was not in force and was therefore ‘a thing writ in water and of no value to anybody’ – to borrow a phrase from LJ Asquith in an entirely different legal context. In this case, Lord Browne-Wilkinson summarised the ‘frustration principle’:

It would be most surprising if, at the present day, prerogative powers could be validly exercised by the executive so as to frustrate the will of Parliament as expressed in a statute and, to an extent, to pre-empt the decision of Parliament whether or not to continue with the statutory scheme.

As I say in the MLR piece in summary:

Cases where statutes directly overlap with prerogative authority come under the abeyance principle. Cases where prerogative executive powers persist and could be used in a way inconsistent with the will of parliament come under the frustration principle. FBU is perhaps the paradigm case because it illustrates so precisely the distinction between overlapping and merely inconsistent statutory provisions. Since the relevant part of the statute was not in force, FBU fell under the frustration principle. If the Act had been fully in force, it would have fallen under the abeyance principle.

The double taxation example

Incidentally, the frustration principle – if accepted – provides an answer to Professor Finnis’s ‘double taxation’ argument. If, and to the extent, the adding or taking away of rights is not in fact actually mandated by statute (see post by Kieron Beal QC), it is entirely plausible to suggest that such changes do not in any way frustrate the intention of parliament regarding the double taxation regime. Such changes are entirely consistent with the purpose of the relevant statutes. The frustration principle is a test not a trap. It can be passed.

This can be contrasted with the Miller situation where the clear intention of the 2002 Act would inevitably be frustrated by executive action under the prerogative. It is plausible to suggest that Miller is in fact a paradigm example of a breach of the frustration principle – at least as the case was argued in the High Court. In the alternative, Finnis may be simply be wrong to assert that the Crown has the power to take away rights under double taxation treaties. He cites no case law in support of his claim. He does not deal with Laker Airways or its progenitor, Article 1 of the Bill of Rights 1689. It may very well be the case that in the event that a case was brought that challenged the power of the Crown to remove rights acquired through the double taxation regime, the courts would give the opposite answer to the one Finnis seems to assume they would.

The core issue in Miller

At least Finnis makes some attempt to deal with the 2002 Act, albeit in a brief paragraph at the end of his supplementary note. I will address that later. What has been most surprising about the wealth of academic commentary that has poured forth since the judgment in the High Court has been the total absence of any persuasive answer to the core issue at the heart of the case. That issue is the Category 3 rights of which the 2002 Act is the best example. The briefest perusal of the Day 3 transcript reveals that Lord Pannick and Dominic Chambers for the claimants both put the 2002 Act at the very heart of their final submissions. It might be thought that this alone would have prompted commentators to at least attempt to address the issue. It is possible that the heavy focus of the High Court judgment on the ECA may have distracted the attention of commentators but even if commentators were right on every single point they make on Category 1 & 2 rights, the claimants could still win easily on Category 3. The inevitable loss of the right to vote for an MEP is by some distance the strongest argument in the claimants’ arsenal.

Those of us who attended every day of the hearing quickly realised that the 2002 Act was gaining more and more importance as the submissions progressed. Once the ‘Categories’ of rights set out by Dominic Chambers QC were accepted by all participants, there was considerable anticipation of the moment when the Government would address the Category 3 rights which included the 2002 Act. The reaction in the court when Jason Coppel QC frankly admitted that on Category 3 rights his case was hopeless, and he had no answer, had to be seen to be believed. Barristers for the claimants were openly agog. Mr Coppel’s exact words were: ‘the category of domestic law rights which will inevitably be affected by notification is very small’ (Day 3: p54). Almost the first thing Lord Pannick said in his Reply was that he only had to show ‘one such right’ would be lost and he would win the case. He was right. The fact that the court decided to go so much further is neither here nor there in terms of the outcome on the core issue.

It is suggested therefore that the appropriate central focus of the discussion must be the 2002 Act. If my ‘statutory basis’ argument is rejected, it is hard to see how any of the arguments put forward by what might be termed the ‘prerogative camp’ could succeed. The frustration principle reveals why.

Academic commentary

It is worth dwelling on just how careful a choice the 2002 Act was by Barber, King and Hickman in their original blog. It neatly circumvents the main arguments of the prerogative camp. Elliott’s ‘uncertainty’ argument claims that a new deal or other alternative outcomes could mean that some EU rights are not in fact removed by triggering Article 50 via prerogative and that we do not at this point know which rights will be lost and which retained. That argument has no answer to the 2002 Act point. Whatever the outcome of negotiations, such that the UK joins the EEA or constructs a bespoke agreement of some kind, it is impossible to avoid the conclusion that elections to the European Parliament will end (as the Government conceded in court). This would inevitably frustrate the clear intention of parliament in the 2002 Act.

Elliott’s ‘from time to time’ argument – and Finnis’s sophisticated restatement of it – is also inapplicable to the 2002 Act. They claim that s 2(1) ECA is only a gateway for whatever rights are currently applicable and that can reduce as well as increase. The 2002 Act, however, is independent of the ECA and triggering Article 50 will inexorably result in the loss of the right to vote, thus frustrating the will of parliament. Hence rights conferred by parliament in the 2002 Act will inevitably be removed by prerogative whim. Elliott has not yet addressed the 2002 Act other than a very brief comment in one blog over the summer.

The 2002 Act issue also undermines the Government’s claim that Article 50 only operates at the international level. If Article 50 is triggered, it will inevitably have the effect of frustrating the intention of parliament to vest voting rights in British citizens in domestic law, whatever its international law consequences might be. The only possible escape route is if Article 50 is revocable.

Feldman repeatedly conflates the abeyance and frustration principle. For example, he says:

One of those principles is that the prerogative ought not to be exercised in a manner inconsistent with an Act of Parliament which occupies the same field as the prerogative.


If, as suggested above, the European Communities Act 1972 cannot be read as impliedly restricting the foreign affairs prerogative so as to prevent the Crown from initiating a procedure for withdrawing from the EU, Laker Airways does not support the Court’s judgment.

Elliott and Hooper also conflate the two principles. They say:

But Fire Brigades says nothing of a situation where the will of Parliament in a particular statute is either (a) unclear, or (b) simply has not been expressed on a particular point. It remains unclear as to whether Parliament really did contemplate the process of leaving the EU when section 2(1) of the ECA 1972 was drafted. It is not immediately (let alone literally) clear whether the wording of section 2(1)… indicates any particular parliamentary intention relating to the process of EU withdrawal.

Each of these examples fails to draw the correct distinction between abeyance and frustration. There is no need for the 2002 Act or the ECA to ‘occupy the same field’ as the prerogative. If it did, the abeyance principle would apply and the foreign affairs prerogative would have disappeared from the scene – whereas both sides are arguing that it is the prerogative that is being used to trigger Article 50. This would be impossible had it been placed into abeyance. Nor is it necessary to read the ECA as ‘impliedly restricting the foreign affairs prerogative’. There is no need to locate ‘any particular parliamentary intention’ relating to withdrawal in the original drafting of the ECA. Instead, the key is whether the exercise of any remaining prerogative does, or does not, frustrate the intention of parliament in any relevant Act.

Finnis on the 2002 Act

The argument put forward by Finnis on the 2002 Act is bold. It is worth setting out:

Parliament itself, by giving statutory approval to TEU art. 50, contemplated the possible destruction by sheer prerogative action of statutory rights including those in the 2002 Act.

Moreover, the 2002 Act discloses no positive intention that there be elections in the UK to the European Parliament, but rather the intention that if and when under EU law there arises an obligation or opportunity for Member states to conduct elections to that Parliament, then such elections shall be conducted in the UK in the manner specified in the 2002 Act. (Emphasis added)

The European Union (Amendment) Act 2008 (‘the 2008 Act’) approved the Lisbon Treaty and therefore Article 50 by inserting it into s 1(s) ECA. It did not incorporate or give legal effect to Article 50. Any authority possessed by Article 50 therefore derives solely from the ECA. However, the ECA also does not incorporate Article 50. Instead, s 2(1) ECA simply gives effect to rights, powers, obligations etc. that are located in the Treaties. This is not the same thing as incorporation at all.

Finnis argues that statutory approval of Article 50 under the 2008 Act explains how some rights can be lost. But this must be a statutory argument and refer only to those rights that enter UK law through the s 2(1) gateway because the 2008 Act only inserts the Lisbon Treaty into the ECA. It is difficult to see how prerogative power could be relevant and even more difficult to see how the 2002 Act could be affected. The insertion of Article 50 into the ECA arguably alters the purpose of the ECA as set out in the long title such that s 2(1) provides a conduit to various Category 1 and 2 rights unless the UK decides to leave the EU. I make this point at length elsewhere. However, rearranging the Category 1 and 2 deckchairs on the Titanic entirely misses the Category 3 iceberg looming menacingly into view.

Finnis claims that ‘statutory approval’ of Article 50 demonstrates that Parliament ‘contemplated’ that rights under the 2002 Act could be lost by the exercise of prerogative power. But this simply assumes precisely what must be proved. Where does the 2008 Act – or actually the ECA into which the 2008 Act inserted Article 50 – amend the purpose of the 2002 Act? If the 2008 Act, or any Act, authorises the executive to do something, then that by definition must be a statutory power not a prerogative power. Statutes do not authorise prerogative powers. The issue should be considered the other way round. Prerogative must be exercised consistently with statute and statutes may, on occasion, leave prerogative powers untouched to be used by the Crown.

It is a wholly novel claim to argue that statute somehow authorises some kind of prerogative power to undermine statutes. It is also, incidentally, wholly novel to claim that somehow there are a separate category of statutory (Category 3) rights that are conditional on executive action under the prerogative of foreign affairs. This is to invent a new category of statutory rights and to import some kind of strange quasi-monist principle into what remains a dualist system. This is not Switzerland.

Finnis’s reference to ‘EU Law’ is also revealing. EU law primarily applies through the ECA ‘gateway’ provisions. How can the ECA affect the 2002 Act? The ECA predates the 2002 Act. ‘Contemplation’ butters no parsnips. The only way for the ECA to alter the purpose or meaning of the 2002 Act is through the use of s 2(4) ECA which famously states that any enactment  ‘passed or to be passed’ must be construed in line with it. But s 2(4) only applies to rights, powers, obligations etc. that pass through the s 2(1) gateway. For the ECA to overcome the 2002 Act would therefore require Article 50 somehow to generate some kind of statutory right under s 2(1) ECA. This is the precise argument I make in the MLR article, but it is not the position of Finnis, Elliott or Feldman, who are arguing that the power to trigger Article 50 remains under the prerogative. And section 2(4) does not apply to prerogative powers, only to relevant EU rights, powers etc. under s 2(1).

The High Court decision in Miller

We must turn finally to the High Court’s judgment in Miller. This also conflates the abeyance and frustration principles. In paragraph 94, the court says that parliament intended ‘to abrogate the Crown’s prerogative powers’ and did so ‘through the ECA 1972’. They also hold that the ECA ‘introduces EU rights into domestic law and must be taken to cover the field’. In 93(2), by contrast, the court appears to apply the frustration principle as well, declaring that the Crown cannot act in a way that is ‘inconsistent’ with the ‘statutory objective’ in the ECA. The finding that the prerogative has been ‘abrogated’ rather begs the question as to how the Crown has been busily agreeing treaties and new rights in the EU using the prerogative of foreign affairs if the prerogative has been in abeyance for 44 years. LJ Sales even raised this issue in oral argument when he asked whether, if the prerogative was abrogated, the Government was suggesting that the 2008 Act caused the prerogative to ‘bounce back’ (Day 2: p161).

The finding that the prerogative has been abrogated has also drawn sharp criticism from commentators, such as Feldman, who have quite reasonably pointed out that it is difficult to locate in the language of the ECA an explicit – or necessarily implied – intention to put the prerogative into abeyance. They are quite right, but this is beside the point. It was not necessary for the High Court to make any such findings – that amounts to seeking to satisfy both the abeyance and frustration principles. It did not have to find that the relevant prerogative was ‘abrogated’ or put into abeyance. The whole point is that the prerogative persists, but may not be used inconsistently with the ECA or, far more importantly, the 2002 Act. The Crown cannot use the prerogative in a way that removes rights parliament intended to and did in fact confer on UK citizens.


This post has sought to clarify an important analytical distinction in the law relating to prerogative and statute that has hitherto been missed. It has suggested that two principles, ‘the abeyance principle’ and ‘the frustration principle’ should be sharply distinguished. It has suggested that if the author’s claims as to the existence of a statutory basis for the Article 50 trigger are rejected, the frustration principle clearly applies to the core argument of the claimants on the 2002 Act. It has further been argued that much of the academic commentary, and even the High Court decision, would be improved if the distinction between the abeyance and frustration principles is adopted. Finally, it has argued that the claimants’ case, properly understood under the frustration principle, is even stronger than has commonly been assumed, unless a statutory power can be located in the ECA to trigger Article 50.

The author would like to thank Gavin Phillipson and Tom Poole for helpful comments on a previous draft. The usual disclaimers apply.

Robert Craig, Law School, London School of Economics

(Suggested citation: R. Craig, ‘The Abeyance Principle and the Frustration Principle’, U.K. Const. L. Blog (16th Nov 2016) (available at