The Westminster Parliament is sovereign and, as section 28(7) of the Scotland Act 1998 makes clear, has undiminished power to make laws for Scotland as well as all other parts of the United Kingdom. However, as set out in Devolution Guidance Note 10, the UK Government has agreed that there are 3 categories of provision that should not normally be enacted in primary legislation at Westminster unless the Scottish Parliament has given its consent. Those 3 categories are:
- provisions that would be within the legislative competence of the Scottish Parliament (i.e. "devolved matters" that could alternatively have been dealt with in an Act of the Scottish Parliament);
- provisions that would alter the legislative competence of the Scottish Parliament (i.e. alterations to the list of protected enactments or reserved matters - as set out in schedules 4 and 5 to the Scotland Act - that could alternatively have been made by an Order in Council under section 30(2) of the Scotland Act);
- provisions that would extend the executive competence of the Scottish Ministers (i.e. functions that could alternatively have been conferred by an Order in Council under section 63 of the Scotland Act).
Therefore, if it is proposed that a Bill at Westminster should contain provisions that fall within any of those categories (or any combination of them), there needs to be a mechanism for giving the Scottish Parliament an opportunity to indicate whether or not it gives its consent. That mechanism, regardless of the category or categories of provision in question, is known generically as a Legislative Consent Motion (formerly known as a 'Sewel Motion' after Lord Sewel, the UK Government Minister who, during the Parliamentary passage of the Scotland Act, gave a commitment that "Westminster would not normally legislate with regard to devolved matters in Scotland without the consent of the Scottish Parliament").