Submitted by: Martyn Doherty
1. ‘What role do constitutional conventions play in British constitutional life?’
In the UK’s ‘ramshackle’ constitution (Poole 2010), traditionally uncodified conventions regulate executive decision-making. From Prime Ministerial resignation following electoral defeat to collective Cabinet responsibility, the starting point has always been that they are exclusively political, their strength evaluated by considering their precedent, binding effect and the reasons behind them (Jennings 1959).
However, with their increased codification and indirect enforcement by the courts, conventions are no longer the ‘unwritten rules of the game’ (Elliott and Thomas 2017). Rather, this traditional role has become overshadowed by their inadvertent weakening of Parliamentary sovereignty.
The Traditional Roles of Constitutional Conventions:
In principle, most constitutional conventions live through ‘political pressure’, using their ‘underlying constitutional values’ to ensure compliance (Elliott 2002; Barber 2009). Attached to this desire to avoid judicial intervention, the traditional rationale for conventional constitutionalism is twofold:
Firstly, Jaconelli (2005) sets out that ‘where the desired outcome cannot be achieved through the instrument of the law’, political conventions may prove useful. A useful example here is Prime Minister’s Questions, held weekly in the Commons. Theoretically, this could be codified. However, given Parliament’s ‘exclusive cognisance’ and Article IX of the Bill of Rights 1689, that ‘proceedings in Parliament ought not to be …questioned in any court’, it is unlikely that the court would intervene to enforce it. Although ‘it [is] unconstitutional for the UK Parliament to do certain things’, the court remains constrained by the Separation of Powers doctrine (Madzimbuto ). In these circumstances, conventions emerge vital: becoming the ‘flesh which clothes the dry bones of the law’ and ensuring political accountability (Jennings 1959).
Secondly, ‘where critical elements in the content of a norm are not suitable for legal analysis’, a political remedy remains vital (Jaconelli 2005). Jaconelli demonstrates this through the Salisbury convention, by which the House of Lords undertakes not to hinder the passage of HM Government’s manifesto commitments through the Upper Chamber.
The issue here is not that legislation would be unable to reform the Lords’ influence; such legislation already exists. Instead, political manifestos, ‘drawn up to allow considerable freedom of manoeuvre’, are ill-suited to the same interpretation given to ‘more carefully-worded’ pieces of primary legislation (Jaconelli 2005). While it does not follow that the Lords are better equipped to make this interpretation, ‘the sanction of any departure’ from its intended meaning is, undoubtedly, better to be political than legal (Bogdanor 2011)
A Halfway House for Law?
Asides being able to incorporate former conventions directly into statute at Parliament, there is support for the view that, over time, long-standing conventions may ‘crystallise’ into justiciable legal principles (Barber 2009). If so, the role of the constitutional convention could be that of a ‘testing ground’, allowing political practices to be refined continuously before eventual becoming law.
Evidential support for this approach comes in two principal arguments. First, it is suggested that the Ministerial Code and Cabinet Manual - as documents collating constitutional conventions together - is becoming ‘a formalised set of rules’ which are ‘crystallising’ into law (Barber 2009). Yet, whilst clearly part of a trend towards codifying constitutional conventions, breaches of the Code remain entirely political. Given the lack of justiciability, this hypothesis remains entirely academic.
More credibly, Barber (2009) and Elliott (2002) also argue that – as the Court’s order of certiorari against the Merchant Shipping Act 1988 in R (Factortame Ltd.)  was entirely without precedent, the court must have been ‘giving legal force to a convention that governed the relationship between English and European law’. Nonetheless, this too falls short.
Firstly, there is no doubt that the principle ratio of the court was not convention, but ideas of Parliament’s self-embracing sovereignty and the implications of section 2(4) of the European Communities Act 1972. Moreover, Jaconelli (2015) points out the central flaw: such a process of ‘crystallisation’ would breach the Rule of Law’s requirement for legal clarity, the court being ‘silent’ on the amount of time that would be required for a constitutional convention to be transposed into law. Without addressing this, it is clear that the court could not have been capable of forming such judgment legitimately, meaning that the role of conventions ultimately is not proven to be a refinery process for common law recognition.
Notwithstanding this conclusion, there are still grounds to suggest that constitutional conventions may, indirectly, be ‘enforce[d]… as an interpretative aid’ in applications for judicial review (Barber 2009).
This more moderate approach attracts stronger judicial backing. For one, it was essential to the court in Miller  to note that HM the Queen ‘was [nothing] other than obliged by constitutional convention’ as the context under which the unlawful advice given by the Prime Minister was executed. Even more impactful, however, was that the court in GCHQ  held that the practice of consulting trade unions – considered by Allan (2016) to be a constitutional convention – could be capable of creating justiciable legitimate expectations for the purposes of judicial review. Consequently, the message to be taken is clear: the direct unenforceability of constitutional conventions as law does not bar their use as grounds upon which other legal rules may be applied.
Difficulties Arising out of Miller:
With the role of uncodified conventions addressed, the role of conventions which have been fully transposed into statutes remains uncertain. Here, the central issue is Miller ’s assertion that ‘[the constitution] includes numerous principles of law, which are enforceable by the courts.’ Prima facie, this is uncontroversial. Yet, as Allan (2016) found of the court in Information Commissioner , the court ‘[imputed] a neat conceptual distinction between convention and principle without addressing their increasing overlap’.
To see the consequences of this, Jaconelli (2005)’s thesis that conventions regulate areas unsuited to statutory legislation is again helpful. Fundamentally, this extends to both Parliamentary Sovereignty (as they may be impossible to entrench in primary legislation) and the Rule of Law, a moralistic ‘political theory’ which appears not unlike constitutional conventions (Craig 1997). Strikingly, it can be concluded that the Rule of law would even satisfy Atiyah (1981)’s test for constitutional conventions: it arises ‘from what people do, not what they agree or promise’.
In this light, it is noteworthy that the court would directly enforce the Rule of Law in Unison  to protect ‘the idea that society is governed by law’ but, in the same year, failed even to give effect to s 28(8) of the Scotland Act 1998, which codified the Sewel Convention on devolved legislative competence. The corollary, Crummey and Ibarra (2018) suggest, was to create a class of ‘statutory’ conventions which ‘do not carry the force of law’. By ruling that s 28(8) only ‘recognised’ the Sewel Convention’s existence, the court reached an illogical conclusion which unduly favoured the Executive over Parliament. More than that, the court ‘devalue[d] the status of Acts of Parliament’, weakening both the Sewel Convention and the sovereignty of the Parliament which sought to give it enforceability.
Today, constitutional conventions remain vital, assuring political responsibility where the law proves insufficient. However, as they become contextually more relevant to a court who fails to accept Parliament’s growing desire to codify them, a convention’s function is no longer exclusively political. With the further damage of Barber’s theory on ‘crystallisation’ of conventions into common law, the current danger is that uncertainty will render vital constitutional conventions obsolete. If this is to be averted, and our political constitutionalism upheld, it must be for the Supreme Court to correct course, no longer pitting tradition against the sovereign will of Parliament.
 See Parliament Act 1911, s 2.