The UK 'in / out' EU referendum and its constitutional law implications.


The highly charged 2014 Scottish independence referendum campaign, and the 2015 Conservative Party promise to hold a national 2017 referendum on continued UK European Union membership have injected new life into a previously secondary UK constitutional law issue.[1]

In this essay, the constitutional implications associated with the anticipated 2017 'in / out' referendum are assessed from three distinct, but inter-related perspectives. The UK legal frameworks providing support for holding a referendum are identified and explained in Part One. In this Part, the otherwise previously limited UK referendum experience is examined. Part Two provides a comparative assessment of other Commonwealth jurisdictional experience with the referendum process, where the 1998 Australian legislation and extensive Canadian constitutional battles waged over Quebec independence provide the forthcoming UK campaign with additional context. [2] In addition to the constitutional implications associated with either possible 2017 referendum outcome, suggested collateral referendum process benefits are explored in Part Three. Greater overall UK citizen democratic engagement potential and prisoner voting rights are key examples.

Part One: UK referendum law

A referendum is generally defined as a direct vote where the entire electorate is asked to vote on a particular proposal, one usually framed as a question to be answered in the affirmative or negative.[3] In many international instances, referendums have been successfully promoted by particular sovereignty campaigners as a peaceful means to pursue independence for a particular people or society from an existing recognised state.[4] Numerous post-Cold War (post-1990) examples include the independence referendums in former Soviet Union territories, the Socialist Federal Republic of Yugoslavia, East Timor, and Montenegro.[5] These referendums were conducted in accordance with the international law principle articulated in the Western Sahara Advisory Opinion: the application of the right of self-determination requires a free and genuine expression of the will of the peoples concerned.[6]

Referendum principles

The leading authorities equally confirm that independence is not an entitlement under international law.[7] On this basis, a referendum is only a necessary but not a sufficient requirement for independence. For this reason, independence referendums are not binding on the central government, unless the government declares itself bound by the outcome.[8] Further, international law does not prescribe the manner in which an independence question must be phrased, or how a referendum 'winner' is defined. Once more, the authorities tend to confirm that a strong correlation exists between referendum outcome reliability, and the referendum question clarity.[9]

Previous UK referendum experience

This Part One title is thus misleading, if understood strictly in its literal UK-centric sense. In the largely unwritten UK constitutional structure, no express sanction is provided for referendums in any circumstance.[10] Prior to 1972, UK constitutional evolution remained largely influenced by the continued state commitment to the rule of law and parliamentary sovereignty, its twin constitutional pillars.[11] The UK decision to join the European Community, as confirmed by the 1972 enabling legislation,[12] signalled a new UK constitutional age. Although not suggested as an always direct correlation, since entering the Community (now EU), 11 UK referendums have been held.[13] With the notable exception of the 1973 Northern Ireland sovereignty referendum, and the 1975 referendum on continued UK Community membership, most of these votes have concerned UK devolution of powers questions.[14]

The specific constitutional authority to hold a referendum is rooted in the parliamentary supremacy doctrine. Its principles confirm that a sovereign parliament may enact any legislation within its power, with the acknowledgement that no parliament is permitted to bind its successor. On this basis, each of the referendums noted above was organised, the vote taken and its results affirmed in accordance with purpose-built legislation. The Scottish Independence Referendum Act 2013,[15] and the current draft EU referendum Bill are examples.[16]

As Tierney observes, the 2014 Scottish referendum was especially remarkable when placed in the broader European referendum experience context.[17] The intergovernmental agreement reached between the UK and Scottish Governments established a framework for the process rules that governed the referendum. The UK Government consensually bound itself to a process that could have precipitated the break-up of the state, a unique level of acquiescence in EU referendum history.[18]


Referendum question clarity is an issue that has percolated throughout the international law scholarship,[19] as well as the specific Canada -Quebec constitutional debates discussed in Part Two. The 2014 Scottish question posed ('"Should Scotland be an independent country?"), and the anticipated 2017 EU 'in / out' proposal are considered against this backdrop. The 2017 question will likely approximate this simple statement: "Should the United Kingdom remain a member of the European Union?"[20]

If one accepts the earlier Vidmar proposition that question clarity and referendum outcome credibility are inextricably linked, these most recent UK examples are ones that lend significant credibility to both government commitment to be bound by the referendum outcome.[21] Further, there is a suggested inherently greater degree of public confidence placed in the selected referendum process when maximum question clarity is attained. A citizen that is asked a straightforward, unambiguous question will better appreciate the ramifications of their vote and the larger outcome, than where the question has variable shades of meaning that are open to post-referendum interpretation.[22] The anticipated 2017 'in / out' question, as with the 2014 Scottish question, is an attractive direct democracy decision-making tool when these various factors are collectively considered.

Referendum - public acceptance as a UK constitutional reform tool

Notwithstanding the relatively small UK engagement with the referendum process throughout its constitutional history, there has been significant scholarly enthusiasm expressed for expanded UK referendum use for a significant period. The 2001 Ewing commentary with respect to how future UK referendums were likely to be conducted is an example.[23] Although Ewing's blunt assertion that the Political Parties, Elections and Referendums Act 2000 (PPERA 2000) would transform the British political system parties from being one of the least to being one of the most highly regulated in Europe may have not entirely found its mark, Ewing was prescient with respect to how referendums would become a staple UK constitutional feature.[24]

As Knock observed with reference to the North East England November 2004 referendum concerning establishment of an elected regional assembly, there was general public satisfaction expressed regarding the process adopted by the Electoral Commission.[25] The Commission, under PPERA 2000 auspices, was able to increase voter turnout over that usually found in municipal elections. This less prominent regional referendum inspired deeper policy-making review of possible future use of all-postal ballots, ways to regulate referendum campaigning, and corresponding media coverage rules.[26] The resolution of these secondary issues associated with the referendum process support this contention advanced by Ghaleigh et al.[27]the PPERA created a substantially novel ecosystem for the conduct of elections and referendums in the United Kingdom so far as matters of party funding are concerned, and will continue to contribute to greater citizen confidence in the political system going forward.[28]

Part Two: Comparative Commonwealth examples

The Australian and Canadian referendum experiences are useful additional perspectives from which to examine the title question. Both nations share a common UK constitutional and social root. Further, in each instance, respective referendum mechanisms were adopted to resolve a specific national issue similar in importance to the pending 2017 UK EU 'in / out' determination. However, both the Australian and Canadian referendum experience have features that effectively underscore the constitutional impacts likely associated with either possible 2017 referendum outcome.


The Australian Constitution makes express provision for referendums as the sole mechanism by which a constitutional amendment can be enacted.[29] The proposed amending legislation must first be passed by both Australian houses of parliament.[30] Alternatively, where only one House approves the proposed law, the Governor-General (on the advice of the Prime Minister) is permitted to exercise a limited constitutional power (the 'deadlock provision')[31] to decide whether to submit the referendum to the people.[32] Where the referendum is mandated by both Houses approval, or otherwise mandated under the 'deadlock provision', the Constitution provides the necessary referendum must occur within six months. The referendum passes where a double majority is achieved, namely: (i) a majority of citizens; (ii) a majority vote in four of the six Australian states.[33]

The notable feature revealed by the Australian commitment to a fixed constitutional amendment referendum process is the relatively few amendments that have successfully passed. Only 8 of 44 amendments have attracted necessary national approval.[34] One might conclude that the entrenched Australian constitutional amendment linkage to national referendum outcome does not tend to precipitate frequent constitutional change.


The Canadian referendum experience more closely approximates that of the UK as discussed in Part One. Prior to 1982, the Canadian constitution had similar features to that of the UK, with a largely unwritten structure where customary powers dominated its structure.[35] The 1982 Canadian adoption of its Charter of Rights and Freedoms, as part of 1981 Constitution Act, has not altered the traditional Canadian avoidance of referendums, except in extraordinary circumstances.[36] The Quebec sovereignty issues that contributed to the 1992 national constitutional referendum and the 1995 Quebec referendum are the two most notable comparable examples in this 2017 UK referendum context.[37]

The most important contribution the Canadian constitutional jurisprudence makes to the present analysis is the 1998 Supreme Court of Canada decision, Re Secession of Quebec.[38] The Court succinctly endorses the general international law principles explained in Part One. It found that Quebec could not, despite a clear referendum result, purport to invoke a right of self-determination to dictate the terms of a proposed secession to the other parties to the federation (the other nine Canadian provinces).[39] Such a democratic vote, by however strong a majority, would have no legal effect on its own. It could not 'push aside' the principles of federalism and the rule of law, the rights of individuals and minorities, or the operation of democracy in the other provinces or in Canada as a whole.[40]

The Court suggests that the only certain outcome from a Quebec majority succession vote based on "a clear majority on a clear question", is the need for the various political actors to negotiate the terms under which succession might occur.[41] It is suggested that the 1998 Supreme Court decision is persuasive with respect to what might transpire between the UK and EU in the event of a 2017 'out' vote.[42]

Part Three: Collateral 2017 referendum benefits

It is suggested that if the 2014 Scottish referendum campaign is an indication, the 2017 pre-referendum period will prompt consideration of additional constitutional issues. The much-discussed prisoner 'right to vote' arguments [43] are a notable example of the issues that were not directly connected to Scottish independence that were well-aired prior to the 2014 vote.[44] Prisoner rights have distinct constitutional implications, given that who is permitted to exercise their franchise is a fundamental democratic consideration.

In Moohan, the Supreme Court majority held that the rule of law could not be interpreted to encompass a universal right to vote.[45] Lord Kerr offers a provocative minority view that may prove influential in the determination of who can vote in the 2017 referendum, particularly given the European Court of Human Rights disapproval of the UK prisoner voting rights limits.[46] His Lordship suggests that as a referendum concerning whether Scotland should become an independent nation would have made a critical difference to the form of government to all Scottish citizens would be subject, the right to vote in this particular referendum should be recognised as an undeniable prisoner right.[47]

A second non-referendum outcome issue attractively advanced in the 2014 referendum build up was the attention directed to the voting age.[48] As Walker observes, 2014 referendum permitted persons aged 16 and 17 to cast their ballot. He describes this as a "...radical departure; never before have people under the age of 18 been entitled to vote in a major British election or referendum".[49] In this age of apparent declining voter turnout, the lower voting age arguably encouraged young people to take an interest in their future in a most positive fashion.


There is little question that the pending 2017 'in / out' UK referendum on continued EU membership will be a most contentious and hard fought campaign. The various discussion threads developed in the three Parts set out above confirms that notwithstanding the fact that referendums are not formally entrenched in the UK constitutional structure, these mechanisms appear to provide a valid, and increasingly well-accepted basis on which UK citizens can effectively participate in charting their nation's future. It is likely the 2017 referendum will contribute to the continued UK acceptance of referendums as a useful constitutional reform tool.


[1] See e.g. European Union Referendum Bill (HC Bill 2) [Online] Available: Read the full article here [20 June 2015]; see also The Conservative Party Manifesto 2015 [Online] Available: Read the full article here [20 June 2015], 30.

[2] Nicholas Aroney, 'Reserved matters, legislative purpose and the referendum on Scottish independence' (2014) Jul P.L. 422.

[3] See Jure Vidmar, 'The Scottish Independence Referendum in an International Context' (2014) 51 Canadian Yearbook of International Law, [Online] Available: Read the full article here 3.

[4] Ibid, 4.

[5] Martin Dixon, Textbook on International Law (7th edn, OUP, 2013), 136, 139.

[6] Re Western Sahara Advisory Opinion [1975] CJ Rep 1, (ICJ), [55].

[7] See e.g. Malcolm Shaw, International Law (7th edn, Cambridge University Press, 2013), 146 re Bosnia.

[8] See Jure Vidmar, Democratic Statehood in International Law: The Emergence of New States in post-Cold War Practice (Hart Publishing, 2013), 190, 196.

[9] See e.g. James Crawford and Alan Boyle, 'Opinion: Referendum on the Independence of Scotland - International Law Aspects' (2013) [Online] Available: Read the full article here [20 June 2015], 71, re 'Principles of state continuity and succession'.

[10] See e.g. Steve Tierney, 'Legal issues surrounding the referendum on independence for Scotland' (2013) 9(3) E.C.L. Review 359, 363 re Edinburgh Agreement 2012.

[11] A point well-entrenched in UK constitutional law commencing with AV Dicey (late 19th century), as explained by A Bradley, C Knight, and K Ewing, Constitutional and Administrative Law, (16th edn, OUP, 2014), 60.

[12] European Communities Act 1972, s. 2.

[13] See UK Parliament, 'Referendums held in the UK' (2015) [Online] Available: Read the full article here [20 June 2015].

[14] Ibid, see also Electoral Commission UK, 'Previous referendums' (2014) [Online] Available: Read the full article here [20 June 2015].

[15] Act s. 2

[16] See European Union Referendum Bill (n 1).

[17] Tierney (n 10), 363, 364.

[18] Ibid; see also Steve Teirney, 'The referendum on Scottish independence: a process as well as an event (Legislative Comment)' (2014) 18(2) Edin. L.R. 245.

[19] See Vidmar, (n 8).

[20] Neil Walker, 'Our constitutional unsettlement' (2014) Jul P.L. 529, 539, footnote 78 re 'in / out' question.

[21] See Vidmar, (n 3), 4.

[22] A point taken from The Economist 'Clarity, please' (14 January 2012) [Online] Available: Read the full article here [20 June 2015].

[23] K D Ewing, 'Transparency, accountability and equality: the Political Parties, Elections and Referendums Act 2000' (2001) Aut P.L. 542.

[24] Ibid, 546, 547.

[25] See Katy Knock, 'The North East referendum: lessons learnt?' (2006) 59(4) Parl. Aff. 682.

[26] Ibid, 684.

[27] Navraj Singh Ghaleigh, Ben Kemp, and Paul Reid 'Politics as a profession: electoral law, Parliamentary standards and regulating politicians' (2012) Oct P.L. 658

[28] Ibid, 660; see also Nigel Knowles, 'No means yes to UK-wide prosperity' (2014) 28(42) Lawyer 12.

[29] Commonwealth of Australia Constitution Act 1900, ss. 51, 127.

[30] Ibid.

[31] Ibid, s. 128.

[32] See Australian Electoral Commission 'Referendums' (2013) [Online] Available: Read the full article here [20 June 2015].

[33] Commonwealth Law Bulletin 'Australia: Electoral and Referendum Amendment Act 1998' (1998) 24(3/4) C.L.B. 730, 732.

[34] Ibid.

[35] As discussed in Patrick Dumberry, 'Lessons Learned from the Quebec Secession Reference before the Supreme Court of Canada' (2004) Secession: International Law Perspectives, Marcelo G. Kohen, ed., Cambridge Univ. Press, 2006, pp. 416-452, 420, 421.

[36] Constitution Act 1981, Schedule B of the Canada Act 1982 (UK), re constitutional amending formula, ss. 38-45.

[37] Dumberry, (n 35), 422.

[38] Reference Re Secession of Quebec, [1998] 2 S.C.R. 217 (Supreme Court (Can)).

[39] Ibid, 226 re 'Question 2'.

[40] Ibid.

[41] Ibid.

[42] A point take from Dan Hamilton, 'A complex divorce' (2015) 2895) Insolv. Int. 80.

[43] See e.g. R. (on the application of Chester) v Secretary of State for Justice [2013] UKSC 63; [2013] 3 W.L.R. 1076 (UKSC), and the controversial limits on prisoner voting endorsed in the Representation of the People Act 1983, s. 2.

[44] See e.g. Scott Blair, 'Electoral law (Case Comment)' (2015) 68 S.H.R.J. 5, and his discussion of Moohan v Lord Advocate [2014] UKSC 67 (UKSC).

[45] Moohan, [38].

[46] As expressed in McHugh v United Kingdom (51987/08) February 12, 2015 (ECHR).

[47] Moohan [69].

[48] Scottish Independence Referendum (Franchise) Act 2013.

[49] Walker, (n 20), 364, footnote 17.