The UK government is expected to mount an immediate legal challenge at the supreme court if the Scottish parliament votes for its own emergency powers over Brexit.



Legal and political sources have told the Guardian it is highly likely that Richard Keen QC, the UK government’s Scottish law officer, would ask the supreme court to strike the legislation down, plunging both governments into a long-running legal and constitutional battle with ramifications for the Scottish independence debate.

A legal source said the attorney general, Jeremy Wright QC, was almost certain to challenge equivalent legislation being considered by the Welsh assembly in the supreme court, if it too voted those powers into law.



The warnings came after Nicola Sturgeon’s government in Edinburgh won cross-party support on Thursday to introduce an emergency bill designed to sidestep Westminster by taking direct control over the repatriation of significant EU legislation into Scottish law.

Scottish and Welsh ministers insist they need these powers in case they and the UK government fail to agree a deal this month on transferring and sharing up to 111 EU powers over areas such as farming, fisheries, environment protection, justice and food labelling which are currently controlled by devolved governments.

Mike Russell, the Scottish Brexit minister, told Holyrood on Thursday it was essential that the devolved parliament was able to protect its interests on its own terms, if the UK government refused to make the concessions he was demanding.

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However, Sturgeon was warned by Holyrood’s presiding officer, Ken Macintosh, earlier this week that the parliament did not have the legal powers to introduce the emergency bill.



In a ruling supported by other senior lawyers, Macintosh said under the Scotland Act 1998, which set up the devolved parliament, it was not entitled to legislate on matters which were still under the control of another body, in this case the European Union.

But that was disputed by James Wolff QC, the lord advocate, who is Scotland’s chief law officer. He gave the bill his seal of approval, while Elin Jones, the Welsh assembly’s presiding officer, also approved her assembly’s emergency bill. Wolff’s advice has not been published, but Russell said the Scottish parliament was able to legislate before something had happened, so long as its powers did not take effect until it had authority to use them.

Senior legal sources say that legal disputes can be resolved only by the supreme court, but UK ministers will be driven by a parallel political contest over which government and parliament is supreme. They will claim their authority and the obligations to act in the interests of the UK cannot be undermined unilaterally by a devolved parliament.



Scottish ministers are currently accusing UK ministers precisely of undermining Holyrood by centralising control in London over EU powers that are currently overseen by devolved governments.

That position was supported in an overwhelming vote in Holyrood on Thursday, when Scottish Labour, the Scottish Lib Dems and the Scottish Green party backed Sturgeon’s government by 86 votes to 27 opposition votes from the Scottish Tories.

The emergency bill will now be fast-tracked through Holyrood over the next three weeks unless the UK, Scottish and Welsh governments strike a deal over how they share out the EU powers at the centre of the dispute.

The UK government, which needs the issue settled before the Lords debates the EU withdrawal bill in mid-March, said it was striving to reach a deal with both governments. Ministers from all three administrations will meet next week to discuss it.

But a spokeswoman confirmed that if Holyrood passed a Brexit bill, UK law officers would consider a legal challenge: “As with all Scottish parliament bills, the competence of this bill will be considered by law officers if and when it is passed.”



Reacting to news of the supreme court option, Steffan Lewis, the external affairs spokesman for Plaid Cymru, the Welsh nationalist party, said: “Westminster’s disgraceful attempt to steal back control from Wales by betraying the unanimous democratic will of the Welsh assembly will fail.”