Do political parties ever carry out “public functions”? Tortoise Media v Conservative Party [2023] EWHC 3088 (Admin)

December 21, 2023

by David Illingworth, current Common Law pupil



On 5 September 2022, the Rt Hon Liz Truss MP was elected leader of the Conservative Party (“the Party”). She was appointed as Prime Minister the following day by the late Queen.

Against this background, Tortoise Media Limited (“Tortoise”) – a British news outlet specialising in investigative journalism – sought information from the Party about its membership procedures. On 17 August 2022, Tortoise wrote to the Party, asking for information on a range of questions including what safeguards were in place to confirm the identity of members, measures to protect against infiltration of the Party, and so on.

As political parties are not subject to the Freedom of Information Act 2000, Tortoise made its request for information at common law and pursuant to Article 10 ECHR. Its right to the information requested would arise only if that information was “state-held information” which the state is under a positive duty to provide where certain public interest criteria are satisfied (as set out in Magyar v Hungary (2020) 71 EHRR 2).

The Party refused Tortoise’s request on the basis that it was not a public body and did not carry out public functions; accordingly, it was under no duty to provide the information requested.

The core issue: was the Party exercising a public function?

Tortoise sought judicial review of the Party’s refusal to provide the information requested. Permission having been refused on paper by Lang J, Tortoise renewed its application for permission before Fordham J. The key issue the court had to consider was whether a political party which selects its new leader, mid-term, whilst the party has a majority of MPs in the House of Commons, could be said to be exercising a “function of a public nature” (HRA 1998 s 6); and/or a public function for the purposes of judicial review (CPR 54.1(2)).

Tortoise advanced three arguments on this core issue. All three of them failed, and permission was accordingly refused by Fordham J in a judgment handed down on 5 December 2023.

Practical reality

Tortoise argued that the court should focus on substance, not form. In reality, the person elected leader of the Party would inevitably go on to be appointed Prime Minister. In effect, the Party was choosing the Prime Minister.

The court held that the specific function carried out by the Party was selecting its new leader; that function was completed on the evening of 5 September 2022. That function had an outcome, but there was not (yet) a new Prime Minister. The fact that the new leader would imminently be appointed Prime Minister was immaterial: “a function is not to be equated with a consequence, including a known consequence”. Fordham J went on to pose two questions to test the validity of that conclusion.

First, was the Party, as a matter of practical reality, exercising the prerogative power of the sovereign to appoint the Prime Minister? No: the Party did not (unlike the executive in Miller) act through the use of the prerogative, or ‘step into the shoes’ of the Sovereign: “the internal party function and the external adoption function are – in substance and reality – distinct.”

Second, could the function exercised by the Party ever be a statutory public authority function? No: the specific function of selecting a political leader “could never be placed in the hands of a statutory public authority”.


Tortoise argued that, in the exercise of a function which leads to the appointment of the Prime Minister, the Party should not be “above the law”; the court needed to exercise its supervisory jurisdiction to ensure there was no shortfall in public accountability.

The court held, in effect, that the Party’s specific function was not justiciable: it was “not one where it is necessary or appropriate for the rule of law and other constitutional principles to be given effect through judicial scrutiny applying judicial review principles”. The court gave two primary reasons for that conclusion.

First, Tortoise’s logic was circular. Any injustice must “begin with the unjust absence of [the court’s] supervisory jurisdiction” over the party’s specific function. In effect, advancing an injustice argument begs the question by assuming there is a public function over which judicial supervision must be exercised to avoid an injustice.

Second, Tortoise was not actually seeking to invoke the court’s supervisory jurisdiction over the Party’s selection of leader per se. Even if that were a public function, the challenge centred on collateral access to information: “this specific function of selecting a new leader is characterised as a ‘public function’, not because there is a need for judicial supervision of that function, but solely as a stepping stone to try to achieve information rights”. As such, there was no “injustice” argument directed to the specific function of the Party in selecting its new leader.

Applying Miller

Tortoise argued, applying the principles established in Miller, that the lawful scope and limit of the prerogative power to appoint the Prime Minister was justiciable, and that whether the lawfulness of the exercise of a prerogative power could also be justiciable was left open. It followed that the Party was exercising a public function because, by selecting its new leader, the Party was in effect deciding the content of the reviewable and justiciable advice to the Sovereign as to appointing a Prime Minister.

The court assumed, for the sake of argument, that Miller supported a scope for reviewability and justiciability in relation to advice to the Sovereign as to the appointment of a Prime Minister. Unlike in Miller, there was no vacuum in constitutional accountability if that prerogative power was misused. On the contrary, if there were any “injustice” in the process by which the Prime Minister came to be appointed, “the safeguarding remedy for the ‘injustice’ lies squarely within Parliamentary accountability and scrutiny”.

Further, even if the supervision of the court were required in the context of the exercise of the prerogative power to appoint a mid-term Prime Minister, the internal Party election process was the wrong target for that supervision: “in so far as there is an act of the executive susceptible to review whose constitutional legality is justiciable in a court of law, it would be the act of the adviser of the Sovereign; not the Sovereign, and not the political party.”


The court’s decision confirms the position in other decided cases: political parties are private unincorporated associations and do not exercise public functions. The fact that one of the functions exercised by a political party is ‘prerogative power adjacent’ does not make that function reviewable or justiciable.

This is by no means the only case in which the exercise of a prerogative power may be subject to challenge. The limits of the Miller doctrine remain unclear, particularly when “the lawfulness of the exercise of a prerogative power within its lawful limits” is at issue. It is not inconceivable that future decisions to enter into (Rwanda) or withdraw from (ECHR) international treaties might bring this issue back to the fore in future cases.