Submitted by: Eli Baxter
Question: Constitutional conventions are essentially political precedents, or expressions of widely shared constitutional values, yet they appear to permeate through every facet of constitutional life in the UK, whether it be legal, or political constitutionalism, and they shape how each constitutional actor exercises their power.
While Dicey (1959) defined constitutional conventions as ‘habits’ or ‘practices’ which govern constitutional actors’ power, Jennings’ (1959) definition is more accurate. Conventions are the ‘flesh which clothes the dry bones of the law’. Constitutional laws form the skeletal frame of the constitution, while conventions endow them with political restraint, preventing a constitutional actor from doing something legally sound, but politically scandalous. The distinction between convention and law is noteworthy. Lardner-Burke  ruled that conventions are not legally enforceable, but why then, do constitutional actors continue to follow them?
The answer, as Jaconelli (2005) realised, is one of constitutional morality, and overarching political fears. For instance, constitutional actors may choose to follow conventions solely because they represent a widely shared constitutional value (Elliot and Thomas 2017). Additionally, fear of political fallout governs a constitutional actor’s legal power. If they were to ignore centuries-old conventions, and violate constitutional values, they would almost certainly be punished at the next election. Conventions therefore occupy an important, symbiotic role with constitutional laws in British constitutional life. Both are required to balance legal power with political propriety.
Dicey (1959) suggested that the ‘full enforceability’ of conventions ‘would dissolve the distinction between convention and law’. Although there appears to be a general accuracy in this contention, it would be incorrect to say that such conventions are not of great relevance in constitutional legal proceedings. As Tomkins (2011) noted, the breach of a convention is ‘every bit as unconstitutional as a breach of constitutional law’, as they are expressions of fundamental constitutional values, and this has influenced the courts in their consideration of conventions in legal proceedings.
Both Attorney-General v Jonathan Cape  and Evans  familiarised the concept of considering conventions in legal proceedings. In Jonathan Cape the Attorney-General sought an injunction to prevent a former cabinet minister’s diary from being published, with specific reference to upholding the collective responsibility convention, and the public interest. Equally, in Evans the government sought to rely on the ‘education convention’ (informing the heir to the throne of government business) to prevent the disclosure of Prince Charles’ correspondence with the government.
The convention-based argument in both cases was unsuccessful, but constitutionally-speaking, it was immeasurably significant. As Vetzo (2018) suggested, it now appears that conventions can play a part in determining whether a legal test (disclosure in the public interest) is satisfied. In that regard, both Jonathan Cape and Evans denote that conventions occupy a nascent-if not active- role in the determination of legal disputes involving constitutional actors and conventions. Although they have only been raised by way of legal defence in a limited number of cases, and are usually unsuccessful, the judiciary have used them as a source of guidance in cases involving major constitutional actors.
Constitutional conventions play an important political role in constraining the cabinet’s power, and ensuring it is held accountable- remembering that it is a creature of convention itself. For instance, the convention of collective responsibility binds ministers to decisions made in cabinet, preventing them from publicly dissenting. This convention occupies a major constitutional role as it binds the most important facet of government together, and ensures they work in the public interest- and not their own. Collective responsibility is unique in that breaches of it almost always result in a ministerial resignation, and since its codification in the Cabinet Manual (2010), this convention has become more authoritative, and therefore, less likely to be exploited.
However, collective responsibility has been suspended on a number of occasions, such as during the Brexit crisis, and ministers with ulterior political ambitions have flaunted its guidance and openly dissented. For instance, when Heseltine broke collective responsibility over Thatcher’s handling of the Westland Chopper Affair, he had in mind the ultimate purpose of succeeding her as Prime Minister. The fact that some ministers would risk resignation in breaching this doctrine would seem to imply that the constitutional role and importance of conventions is prone to violation and will always hinge on how authoritative constitutional actors perceive them to be, as well as their underlying political ambitions.
Similarly, a number of conventions exist within the House of Lords to prevent them from impairing the efficiency of the democratic lower house. The 1945 Salisbury Convention is of the most significance, and it obliges the Lords to give second readings to bills which represent government manifesto promises. There is a strong constitutional reason for this convention, because in its absence, the House of Lords could legally annihilate the democratically mandated government’s proposals whenever they desired, causing serious constitutional fallout. If the Lords repeatedly defeated manifesto commitments, protests about their undemocratic nature would certainly arise, substantiating Jaconelli’s assertion that conventions are followed out of political fear and are thereby an important means of ensuring constitutional actors do not venture into ‘grey’ areas of their power.
Wider Constitutional Significance
Constitutional conventions play a vital role in the devolution settlement, through the ‘Sewel Convention’, which provides that Westminster ‘will not usually legislate’ in devolved matters without permission (Section 2 Scotland Act 2016). In R (Miller) v Secretary of State for exiting the European Union  the Scottish government sought to rely on this convention to prevent Westminster from legislating for them with regards to an EU withdrawal bill. However, the court determined that they could not give a ruling on the scope of the convention, as this was a ‘question for the political world’. With respect to the Supreme Court, the ‘strikingly narrow view’ (Elliot 2017) of conventions adopted in Miller is hard to reconcile with Evans and Jonathan Cape, as it seems to discard the established significance of conventions in legal disputes with constitutional ramifications.
However, the nature of Brexit crisis, and its constitutional ramifications arguably influenced the court in neglecting the role of the Sewel convention. If consent from each devolved assembly was required, this would have undermined the premise of Brexit itself, if each devolved assembly could effectively dictate their own terms for exiting the EU. In that regard, one could contend that the more significant the ramifications of a constitutional determination, the less relevant conventions become in the wider British constitutional sphere. Miller is not an accurate semblance of the role conventions play in devolution, and their wider constitutional relevance. The gravity of Brexit led the court away from political determinations, and consequently- away from conventions.
Constitutional conventions occupy an important- if not vital- role in British Constitutional life, assuming significant positions within both the political, and legal sphere. As much of the British constitution is unwritten, conventions are necessary to control, for example, the non-statutory power of the Prime Minister. However, the trend towards codifying conventions has blurred the distinction between convention and law, causing some conventions to ‘crystallise’ into laws over time (Barber 2009). Although the codification of conventions does not immediately impact British constitutional life, without their flexibility, the important role of conventions in British constitutional life will be diminished.