Scottish independence referendum: legal issues

On 18 September 2014 Scotland voted in an independence referendum. It was said at the time that the process was beyond legal doubt. Not only had the Scottish and UK governments agreed to honour the outcome, but both Holyrood and Westminster had temporarily guaranteed (via a statutory device known as a Section 30 Order) that the Scottish Parliament would have the legislative competence for that historic event.

The “Edinburgh Agreement”, however, paused rather than resolved disagreements over the Scottish Parliament’s ability to legislate in this area. The Scottish Government maintained that a referendum of some sort was already within its devolved powers. Successive UK Governments, on the other hand, maintained that it was reserved to Westminster.

Even in 2014 this debate was not new, having first arisen during parliamentary debates around what became the Scotland Act 1998 (“the 1998 Act”). And having been paused between 2012 and 2014, the arguments resurfaced following the European Union referendum in June 2016. By 2020-21, the Scottish Government was indicating that the question might have to be referred to the Supreme Court.

If referendum legislation were to be referred to the Supreme Court, the starting point for its Justices would be the 1998 Act itself. Under section 29(1), Acts of the Scottish Parliament which fall outwith its legislative competence (or powers) are “not law”. An Act (or a provision thereof) is beyond competence so far as it “relates to reserved matters”. Reserved matters are set out in Schedule 5, Part 1 of which reserves “aspects of the constitution” to Westminster. This includes, among other things, “the Union of the Kingdoms of Scotland and England” and “the Parliament of the United Kingdom”.

The 1998 Act also provides a set of principles to assist the courts when approaching questions of competence. Those questions are also known as “devolution issues”. Whether a provision of an Act “relates to” a reserved matter is to be determined “by reference to the purpose of the provision, having regard (among other things) to its effect in all the circumstances”.

Although the UK and Scottish governments agree that the Scottish Parliament cannot unilaterally end the Union (i.e. enable Scottish independence) they differ as to the “purpose” and “effect” of referendum legislation. They therefore disagree whether it would necessarily “relate to” reserved matters. Constitutional academics are also divided. This disagreement is not only legal, but political and historical, concerning differing sources of “sovereignty” as well as competing political mandates.

This briefing paper at first summarises the constitutional development of the United Kingdom of Great Britain and Northern Ireland, including past means of secession from the UK and its former Empire. It then examines debates prior to the creation of the Scottish Parliament in 1999 before tracing the Scottish Government’s attempts to legislate for a referendum in 2010-11. It looks at the debates and negotiations which led to the 2014 referendum, as well as subsequent requests for a s30 Order. Finally, it examines recent legislative and legal developments in Scotland, including the Lord Advocate’s referral of draft independence referendum legislation to the Supreme Court in June 2022 and the Court's judgment in November 2022.