Whereas the intergovernmental Council mentioned above can deal with disputes of a political nature the UK Supreme Court (UKSC) deals with legal disputes on devolution, such as whether the action of a devolved institution is acting ultra vires or beyond its legal competence.
This issue can be taken to the UKSC in one of three ways, namely by:
- A reference from a devolved or UK law officer, such as the UK’s Attorney General (AG) or the Scot’s Lord Advocate. The reference must be after the bill has been passed but before it receives Royal Assent.
- An appeal from certain courts.
- A reference from certain appellate courts.
For example, when the Welsh Assembly legislated to regulate the wages of agricultural workers in Wales, the AG referred the bill to the UKSC where he argued that the provision related to employment and industrial relations (not devolved), rather than agriculture (devolved). The court found against the AG on the grounds that although the provision fell within both spheres the devolution legislation did not require that a provision fell exclusively within a devolved sphere.
Scottish independence referendums
Under the Scotland Act 1998 the following aspects of the constitution are, among others, reserved matters:
- ‘the Union of the Kingdoms of Scotland and England’, and
- ‘the Parliament of the United Kingdom’ a matter which includes the sovereignty of the UK Parliament.
- The 2014 referendum on Scottish Independence was within Scotland’s legislative competence because in 2013 an Order in Council modified the reservation to enable the Scottish Parliament to pass the relevant legislation.
- The Scottish Independence Referendum Bill drafted by the Scottish Government and referred to the Supreme Court by the Lord Advocate was outside the legislative competence of the Scottish Government because it related to reserved matters, and hence if passed it would not be law.
 Agricultural Sector (Wales) Bill, Reference by the Attorney General for England and Wales  UKSC 43.
 Scotland Act 1998, Schedule 5, paras 1(b) and (c).
 Reference by the Lord Acvocate of devolution issues under para 34 of Schedule 6 to the Scotland Act 1998  UKSC 31, §76.
 As provided for inn Scotland Act 1998, s30(2) and as considered in the case above, §5.
 Reference by the Lord Acvocate of devolution issues under para 34 of Schedule 6 to the Scotland Act 1998  UKSC 31, §56, 57, 70-83, 92.