Westminster is sovereign and cannot be prevented from legislating on any matter by the Scottish Parliament, including triggering Brexit, the Supreme Court has been told on the second day of a historic constitutional case.
In a legal argument that goes to the heart of the devolution settlement, the UK Government’s top Scottish law officer told 11 Supreme Court justices that Westminster can “legislate at any time on any matter” and said the convention requiring it to consult Holyrood is not legally enforceable.
Attorney General for Scotland Lord Keen QC was taking part in a legal case that will decide whether Prime Minister Theresa May can use the royal prerogative to trigger Article 50 of the Lisbon Treaty and start the two-year Brexit process without parliamentary approval.
The landmark hearing at the UK’s highest court follows a ruling by the High Court in November that ministers had to seek the approval of Westminster.
Scottish ministers are intervening the case to argue that the Scottish Parliament must also be consulted before Article 50 is triggered.
Lord Keen argued that the Scottish Government’s case was “fatally undermined” because foreign affairs powers, including relations with the EU, are reserved.
Even in relation to reserved matters, Lord Keen said, “the correct legal position is that Parliament is sovereign, and may legislate at any time on any matter”.
He also argued that a convention that dates to creation of the Scottish Parliament giving MSPs a say on UK legislation “was never intended to be a justiciable legal principle”.
The then junior Scotland minister Lord Sewel set out the convention that Westminster should not pass legislation that deals with devolved matters without consulting MSPs, using a parliamentary device known as consent motion.
Following the independence referendum, the Sewel Convention was included in the 2016 Scotland Act following a recommendation from the Smith Commission that it should be “put on a statutory footing”.
However, Lord Keen yesterday argued the convention was a “political” device that cannot be enforced in law, describing it as a “self denying ordinance” for Westminster.
The arguments drew an angry response from SNP MP Pete Wishart, who tweeted: “There’s your Tory Westminster Scottish law officer saying Scotland shouldn’t have a say on Brexit. Know your place, Scotland.”
Lord Advocate James Wolffe is expected to put forward the Scottish Government’s case today. Arguments will conclude this week, with a ruling not expected until January.
Yesterday government QC James Eadie QC rejected the suggestion that its Brexit strategy was an “affront” to Parliamentary sovereignty, and the Supreme Court also heard the first arguments on behalf of claimants bringing the case.
Lord Pannick QC told justices that “the prerogative power to enter into and terminate treaties does not allow ministers to nullify statutory rights and duties” created when the UK entered the EU.
He told the court: “Parliament is sovereign. What Parliament created only Parliament can take away.”
If the court ruled in favour of the government, he argued, it would mean that the 1972 European Communities Act - which paved the way for the UK to join the EU - would, “far from having a constitutional status”, have a “lesser status” than the Dangerous Dogs Act.
Lord Pannick said it would be “quite extraordinary” if that Act “could be set at nought by the actions of a minister acting without Parliamentary authority”.
He stressed that the claimaint’s case did not “deny any effect” to the referendum vote in favour of leaving the EU.
“The referendum is plainly an event of considerable political significance,” Lord Pannick said, “but the political significance, whatever it is, is not, with respect, a matter for this court.
He told the justices: “We are submitting that there is simply no prerogative power to interfere, frustrate, nullify a statutory scheme.”