The Supreme Court will hear arguments over a potential second independence referendum over the next two days.

The SNP and Scottish Greens both pledged to hold a new vote if elected to the Scottish Parliament, and later formed a coalition government.

However, the UK government will not grant a section 30 order to transfer the powers to hold a vote to Holyrood.

Matters concerning the union are reserved to Westminster, but the Scottish government will argue that it should be able to hold an advisory plebiscite in October 2023.

The SNP itself has also submitted a written argument based on the UN right to self determination.

The UK contends that the court does not have jurisdiction in the matter, as a bill is yet to pass through parliament, but that if it does holding a referendum is not lawful under Holyrood's devolved powers as it represents a constitutional issue.

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Westminster insists "A referendum is not, and is not designed to be, an exercise in mere abstract opinion polling at considerable public expense. Were the outcome to favour independence, it would be used...to seek to build momentum towards...termination of the union and the secession of Scotland."

The five judges will hear arguments on Tuesday and Wednesday, with a verdict likely to be published later in the year.t

Their judgement is likely to come down to how narrowly the phrase "relates to" in the Scotland Act, referring to matters of the union, should be interpreted.