Much was made of comments made by the First Minister on the Andrew Marr show on Sunday – leading to reports that she had suggested the Scottish Parliament could ‘veto’ Brexit.

The First Minister did not use that expression – and the suggestion that there might be a veto represents a misunderstanding of the mechanisms that exist for involving the Scottish Parliament in decisions taken by Westminster.

Since the creation of the Scottish Parliament in 1999 there has been a convention – originally called the Sewel Convention and also now known at the “Legislative Consent Convention” – that whenever the UK Parliament looks to legislate in an area that also falls within the devolved powers of the Scottish Parliament it will seek Holyrood’s consent to that legislation.

The convention was formalised in the Scotland Act 2016 which provides that “it is recognised that the Parliament of the United Kingdom will not normally legislate with regard to devolved matters without the consent of the Scottish Parliament.” A second part of the convention (despite not appearing in the 2016 Act) is that the same consent will be sought for Westminster legislation to alter the Scottish Parliament’s powers.

This convention is potentially relevant to Brexit on the basis that, as matters currently stand, the Scottish Parliament and Government are forbidden from breaching EU law. Some constitutional lawyers therefore argue that any legislation by Westminster to give effect to Brexit would require amendments to the Scottish Parliament’s powers to remove that prohibition on breaching EU law, and so engage the convention that Westminster should seek Holyrood’s consent before amending the scope of its powers.

Whether or not this conclusion is correct, the key point from a legal perspective is that the convention is just that: it is not binding in law. A failure by the UK Parliament to seek consent would have purely political ramifications: as would a refusal by the Scottish Parliament to give that consent. That the ramifications would be political rather than legal does not of course diminish their potential importance.