Has the court in Miller (No 2) done the very thing it said it wouldn’t do in Miller (No 1)? Has it given legal enforceability to the constitutional convention of ministerial accountability? Several authors appear to suggest that is has (here, here and here). Indeed, conventions were given rather peculiar judicial treatment in Miller (No 1) not least when placed against Miller (No 2), but also due to the general unenforceability of ‘statutory conventions’ (more here). But back to the apparent elevation of the convention of ministerial accountability (CoMA) to a constitutional principle – or what I refer to as the principle-isation of the convention.
Mark Elliott has resolutely argued that the CoMA was not elevated to a constitutional – and therefore legally enforceable – principle (here). It is worth unpacking his claim a little more. He writes that the court took ‘legal cognisance of the underlying constitutional reason or principle that underpins and animates the convention of accountability to Parliament’ which is the constitutional principle of parliamentary democracy. He goes on to further state that:
‘there is no reason why this constitutional principle cannot both underpin a constitutional convention — and thus institutionalise a required mode of political behaviour — while also serving as a constitutional standard to be applied when lawfulness of executive action by reference to the scope of its legal powers. This does not amount to judicial enforcement of a constitutional convention.’
What he is saying is that constitutional principles give conventions the normative weight that bind actors of the constitution). However, Steven Spadijer offers a slightly more terse reading of the case:
‘The Court has now moved from being a passive observer of political convention to an active player, indeed umpire, of political convention and etiquette. It has attempted to do indirectly what it could not do directly. That is, it has sought to enforce legally unenforceable conventions of responsible government by distilling a general principle of accountability implicitly underpinning those conventions (executive accountability), and then transforming that general principle into a legally enforceable one against the Crown, a legal principle that almost everyone who ever lived had somehow missed.’
The difficulty as to which of these is correct lies in the fact that the constitutional principle of parliamentary accountability is very similar, in practice, to the convention of ministerial accountability. Given these tensions, I want to briefly focus on one possibility of the principle-isation of the CoMA.
What might the effect be on military deployments?
The current arrangement is that the PM has sole prerogative power to deploy military personnel for conflict abroad (except for, controversially so, Drone attacks). In 2003, a convention developed to invite Parliament to vote in a non-binding resolution on deployments. Despite an ex post factum vote (Libya 2011), the absence of parliamentary votes on non-conflict deployments (see here and here), the convention was seen as pretty solid, particularly after 2013 when Cameron honoured the will of Parliament not to militarily intervene in Syria despite his desire to do so. The convention is clearly to enact the principle of parliamentary accountability though of course various limitations exist in a system where, as Bagehot describes, there is a ‘fusion of powers’ between the executive and legislature.
In April 2018 Theresa May launched air strikes in Syria without any parliamentary vote. Despite leading legal commentators arguing that the air strikes were illegal under international law, arguably this fell within the convention that allows exceptions for humanitarian intervention which the PM’s policy paper outlined.
Were a future court to interpret this CoMA as a constitutional principle as Miller (No 2) appears to do, how might it effect military deployments? Would the exercise of the prerogative power to deploy troops without a parliamentary vote (enacting this principle of parliamentary accountability) have ‘the effect of frustrating or preventing, without reasonable justification, the ability of Parliament to carry out its constitutional functions as a legislature and as the body responsible for the supervision of the executive.’ ?
The court in Miller (No 2) stated that the ‘principle is not placed in jeopardy if Parliament stands prorogued for the short period which is customary’ , so not all prorogations are unlawful. This begs the question; if we were to consider the CoMA a constitutional principle, what would a deployment decision look like that frustrates or prevents the ability of Parliament to carry out its constitutional function?
In the case of prorogation, the answer to this question appeared to be fairly straight forward given that length (and one cannot completely ignore the context of the prorogation), though not determinative, was instructive of whether the prorogation was principle-compliant. What a deployment that violates the principle of ministerial accountability may look like ‘is a question of fact which presents no greater difficulty than many other questions of fact which are routinely decided by the courts.’ 
Now if a deployment decision circumvented any parliamentary involvement this may prima facie be contrary to the constitutional principle of parliamentary accountability and provide the courts with a legal standard against which to review such prerogative powers. Taking the convention as the template, this would require an ex ante vote (rather than mere scrutiny). Where the unlawfulness of prorogation is contingent on the length of the time, it would appear that any deployment which truncates or elides Parliament altogether, would be unlawful, save for a reasonable justification. This requirement maybe strengthened for deployments which are pre-meditated and refer to remote threats (polemically referred to as anticipatory or pre-emptive self-defence) or threats to allies (‘collective self-defence’).
But it is here that we begin to run into some problems. Judicial deference to the executive on decisions of national security may dictate the nature of parliamentary involvement, actually only requiring a simple ex ante (or even ex post) discussion in the Commons as satisfaction of the principle of ministerial accountability rather than a parliamentary vote. In addition, the PM would have open to them the ‘reasonable justification’ caveat in the event that the deployment was not principle compliant. The Cabinet Manual may be instructive as to examples of such exemptions to include ‘when there was an emergency and such action would not be appropriate.’
Further, judicial deference to the executive over issues of national security may also enable a ‘security’ exception – a caveat which has been drafted into previous legislative attempts – which would arguably constitute a ‘reasonable justification’. Indeed, Lord Bingham stated in A v Secretary of State for the Home Department that there should be strong deference to the Government’s assessment of the nature of threats posed to national security because the executive are ‘called on to exercise a pre-eminently political judgment’. Finally, the convention has also developed to provide humanitarian intervention as an exception to a parliamentary vote as was the case in April 2018. Thus, taking the convention as a template for the principle, it is likely that this would provide another ‘reasonable justification.’ However, whilst previously the courts would have been happy with legal assurances by senior civil servants affirming the nature of threats, R (on the application of Mohamed) v Foreign Secretary (No 2), has suggested that the courts are now more willing to avoid the deference that national security claims invite. Indeed, the same scrutiny could be extended to claims on emergency and humanitarian grounds too. It would be incumbent on the courts to require detailed reasons for the justification and not simply assume executive innocence.
After all of that, we appear to be back to square 1, whereby the principle-isation doesn’t give the courts any more teeth in reviewing deployment decisions. It seems as if the reasonable justification exceptions swallow the principle-compliancy rule. However, given that failed legislative attempts which would legally require Parliament to vote on military deployments may be undone by Article 9 rights protecting Parliamentary Privilege, (unless, of course, that provision was explicitly repealed or an exception was made for deployment decisions – very unlikely), this could present a small possibility of reviewing the legality of deployment decisions – especially important in light of the litany of failures that the Iraq Inquiry illustrated. A military deployment that was a pre-meditated attack akin to anticipatory, pre-emptive self-defence or collective self-defence (i.e. not an emergency, security or humanitarian deployment) and in which Parliament were unable to scrutinise or vote on the deployment would not be principle compliant and could be reviewed by the courts. The parallel weakening of the national security bar on justiciability and the seeming elevation of CoMA to constitutional principle, may yet envisage a possibility where deployment decisions would, finally albeit narrowly, be reviewable by courts.
The author would like to thank Professor Alison Young for her comments.
Tanzil Chowdhury is a Lecturer in Public Law at Queen Mary University of London.
(Suggested citation: T. Chowdhury, ‘Miller (No 2), the Principle-isation of Ministerial Accountability and Military Deployments’, U.K. Const. L. Blog (24th Oct. 2019) (available at https://ukconstitutionallaw.org/))