Supreme Court hearing on Holyrood's Brexit bill kicking off now - submissions from UK law officers expected to take up most of today. Might also be time for the start of the Lord Advocate's response, which will continue tomorrow. Live stream here: supremecourt.uk/live/court-01.… 
Advocate General for Scotland Lord Keen leading for UKgov side at the Supreme Court. He says the Scottish Brexit bill as an entirety "impermissably modifies" Westminster legislation and as such is outside Holyrood's competence
Lord Keen says EU Withdrawal Bill allows for devolved administrations to go their own way in future - but "starting point" must be "a regime that applies across the entire country". So Holyrood only competent to modify retained EU laws "after exit"
As a spectator sport, this Supreme Court hearing may be lacking in political fireworks - as Lord Advocate notes in his written case, this hearing is going to be "strictly issues of law". Will be *very* technical. But implications are potentially massive... parliament.scot/S5_Finance/Gen…
Lord Keen says Holyrood's Brexit bill is "fundamentally inconsistent with the purpose and scheme of the UK Act" (the Withdrawal Bill). Would create "a parallel body of retained devolved EU law subject to different, and indeed lesser, controls".
Lord Keen's argument is that allowing the Scottish Brexit bill to stand alongside the EU Withdrawal Bill would create "dual, inconsistent regimes", causing "confusion and uncertainty"
Lord Keen: Holyrood Brexit bill is "plainly and directly inconsistent with the UK Act at the most basic of levels, and its mechanisms directly frustrate the purpose of the UK Act". Would prevent creation of a "single cohesive body" of retained EU law across the UK
Lord Keen notes that there are parts of the Scottish bill which do not mirror the Withdrawal Bill, such as incorporating the Charter of Fundamental Rights. Repeats argument that having "dual and inconsistent regimes" would "undermine" the UK legislation
Lord Keen moving on to the Sewel convention of devolved consent now - notes that although it is reflected in legislation that Westminster would "not normally" legislate across devolved areas without consent, it is "non-justiciable" (as Supreme Court underlined in Article 50 case)
Lord Keen contends that Holyrood's Brexit bill concerns "the reserved matter of international relations". "Withdrawal from the EU is a matter for the UK parliament, and the devolved administrations do not have a parallel legislative competence" in that area.
Judges questioning whether Holyrood Brexit bill touches on international relations, if it's intended for use *after* Brexit; Lord Keen says extent to which EU law is retained will impact on relations with the EU, and could affect future talks over regulations & standards.
Lord Sumption notes that Lord Keen's argument is meant to be about the bill as a whole, but he's now "shifting the focus towards specific provisions" - these are "two completely different submissions". Lord Keen says he's just giving examples of problems of "dual system"
Lord Keen says "the constitutional kaleidoscope is being shaken" by Brexit
Lord Keen says the existing devolution framework was designed with EU membership in mind, and "doesn't cater for withdrawal from the EU". "One has to take all of this in context."
Afternoon arguments continuing in much the same vein as this morning's - Lord Keen says EU Withdrawal Bill sets out provision for retained EU law for "entirety of the UK" - legislation is a "protected enactment", so it is "not competent for the Scottish Parliament to modify it"
Lord Keen now arguing that Holyrood is attempting to amend the terms of devolution via the continuity bill. "The Scottish Parliament cannot determine its own competence."
Lord Keen says argument that Scottish continuity bill has the same basis in law as the EU Withdrawal Bill is "simply misplaced"; Westminster is sovereign, and "untrammeled by the legislative constraints" placed on @ScotParl. WM is sovereign, Holyrood is not.
Lord Keen says "the Scottish Parliament is not a soothsayer." Holyrood cannot legislate for what happens after Brexit, because it's not yet 100% certain what its powers will be at that point.
Lord Keen questions what precedent could be set if Holyrood is allowed to set its own competence for a "hypothetical" future scenario. What would be next, he asks - an independence referendum bill? Even an independence bill?
Lord Advocate James Wolffe up now, in defence of Holyrood's Brexit bill. Opens by stressing that case must be decided strictly on points of law, not points of "policy" about whether the bill itself is "wise or foolish"
Key pillar of Advocate General's argument was that Holyrood bill seeks to modify a protected UK bill, in Withdrawal Bill - but it only passed *after* Scottish bill. Lord Advocate now questioning whether the Scottish bill competent was *at the time it was passed*
Lord Advocate says Scotland Act carefully leaves Holyrood free to legislate on areas covered by protected enactments, as long as it doesn't "modify" them. If Westminster wanted to blank off a whole field from Holyrood legislating on it, it would have just reserved it.
Getting pretty technical now, but basically the Lord Advocate's argument is that EU law isn't a reserved matter. Holyrood can legislate on it as long as it doesn't directly modify specifically protected UK statutes.
Lord Advocate says "withdrawal from the EU does not return the domestic constitution to the position it was before 1998 - it takes place with a domestic constitution as it is now, in particular the devolved settlements". EU law has "changed beyond all recognition" since 1998
On claim that continuity bill cuts across reserved field of international relations, Lord Advocate says this is a "narrow and specific reservation", which Advocate General was applying too broadly. Scottish bill was just "providing for continuity of laws on and after exit day"
Lord Advocate: "I say the bill, given it has effect only in the domestic legal order, cannot affect the UK's negotiations with the EU. Those are matters entirely for the UK govt." Basically: not everything involving Brexit is a reserved matter of international relations.
That's all for day one of the hearing at the Supreme Court - Lord Advocate James Wolffe will continue his submissions defending Holyrood's Brexit bill tomorrow, when we'll also hear from Welsh & Northern Irish representatives.
...and we're back. Lord Advocate James Wolffe back up addressing Supreme Court on matter of Holyrood's Brexit bill. Opens by noting that he adopts his written argument in full - which you can read here: parliament.scot/S5_Finance/Gen…
Getting technical, as Lord Advocate addresses the meaning of the word "modify" - Holyrood can't modify some WM legislation which is placed on a protected schedule. LA says this "doesn't create a reserved field" - MSPs can legislate as long as they don't directly "amend or repeal"
Judges ask some helpful Qs to unpack thrust of this argument in slightly plainer English - Lord Advocate says "if the *effect* of the original enactment remains intact, there is no modification". Arguing that continuity bill doesn't modify WM's power to legislate for Scotland
Lord Advocate now arguing that Holyrood has right to legislate for future events ("deferred commencement" of laws) - so MSPs could legislate "in anticipation" to prepare for leaving the EU, while still subject to EU law. This is a "perfectly practical" approach
Lord Advocate says "the UK is proceeding on this analysis", that it can legislate now for things that will happen at the point of Brexit (via Withdrawal Bill) - Lord Sumption appear to agree, saying that "the principle should be identical whichever parliament you are looking at"
Brexit is "not hypothetical", says Lord Advocate - it is "a known future event which will take place imminently". If Westminster has the right to legislate for it now, then Holyrood should too - and doing so is "plainly not" clashing with EU law
Lord Advocate says EU law "envisages that a member state may withdraw from the EU" - after Article 50 triggered, "it is not incompatible with EU law" for member states to prepare for this. "Legal certainty and legal continuity are, after all, principles of EU law"
Lord Advocate repeats that leaving the matter of the UK leaving the EU in March 2019 is "not hypothetical".
"You're perhaps more confident of that than some people," notes Lord Reed drily.
"You're perhaps more confident of that than some people," notes Lord Reed drily.
Court now debating thorny issue of timing. Is the question whether Holyrood's bill was within competence *at the time it was passed* (before the EU Withdrawal Bill had been passed), or does competence refer to the time at which it *becomes law* (so after EUWB got Royal Assent)?
Crux of the Lord Advocate's argument: "The Scottish bill was passed many months ago - it was not intended to modify the UK bill and could not do so."
On "keeping pace" powers in continuity bill, which would let ministers follow changes in EU law post-Brexit - Lord Advocate arguing that Withdrawal Bill doesn't prevent Scottish ministers from "making provision corresponding to provisions in EU law having effect after exit day"
UK case argued that Scottish bill creating dual systems of retained EU law within UK is "frustrating the intentions" of the Withdrawal Bill (to create a single body of retained law) - Lord Advocate says its hard to see this, UK bill has "simply not addressed" keeping pace powers
Court discussing what would happen if judges strike down any part of the bill - would be down to MSPs to "address the particular issues the court has identified" and make changes. Lord Reed suggests it would be "troublesome" for judges to set out legal guidance section by section
Proceedings have gone into a labyrinth of subsections and differentiation between provisions for fixing powers; basically, Lord Advocate says the "parallel" powers Scottish ministers would get under continuity bill are drawn on "narrower terms" than those of EU Withdrawal Bill
The Lord Advocate has concluded his case; Supreme Court now hearing from Michael Fordham QC, for Counsel General for Wales. Here's his written case (backing competence of devolved parliaments to legislate for Brexit): gov.wales/docs/cabinetst…
Mr Fordham (for Welsh govt) says devolved parliaments ARE competent to legislate for Brexit; UK parliament "can impose a new restriction" on this, as laid out in Gina Miller case, but the "baseline starting point" is that the devolved parliaments have competence
Welsh govt QC says legislating for withdrawal from the EU is *not* a reserved matter, as UK law officers claim - "that's an extravagant claim, which has very alarming logical implications". If that really cuts across international relations, "none of this is going to work".
Mr Fordham (for Welsh govt) says UK argument has been "illuminated as being wrong and incoherent". Idea that post-withdrawal statute book is a matter of international relations "just breaks down at every step"
The Lord Advocate appears to be thoroughly enjoying this support...
The Lord Advocate appears to be thoroughly enjoying this support...
Mr Fordham says devolved parliaments can "perfectly properly" legislate for statute book post-Brexit. If UK parliament can do it, why shouldn't others? "The rule of law must be the same for everyone", core values of constitution must apply to all
Northern Ireland Attorney General John Larkin next up at the Supreme Court - here's his written submission, which argues that Holyrood's Brexit bill is "within the legislative competence of the Scottish Parliament" attorneygeneralni.gov.uk/sites/ag/files…
Coming back to the issue of timing (of when the bill needs to be competent, at point of passing, or on getting royal assent and becoming law), Mr Larkin says Holyrood has "done its work" on the continuity bill - would be odd if it was "retrospectively" found incompetent now
Lots of the case law referred to here has been Lord Hope's judgement in Imperial Tobacco vs Lord Advocate - Richard Keen was the QC for the appellants, James Mure (LA's junior today) was there for the respondents and three of today's judges were on panel...all on familiar ground!
Mr Larkin (NI attorney general) wraps up his submission saying Holyrood's Brexit bill is "elegantly and adroitly drafted" - "it may have caused teeth to gnash in Whitehall" with some of its provisions, but it could operate successfully.
UK law officer Lord Keen now responding to some of the arguments heard today - he says "it is clear that the intent of the Scottish bill is to affect the operation of the UK bill". Adds that bill "amounts to modification of the UK act"
Lord Keen says "withdrawal from the EU is unquestionably a matter of international relations", and legislating for statute book post-Brexit is "inextricably bound up with the issue of withdrawal itself". Argument is that this is a reserved matter which Holyrood can't legislate on
Lord Keen says Scotland Act setting out Holyrood's powers "did not anticipate Brexit" - "it is a matter for the UK parliament to determine where areas of current EU competence may appropriately lie in the event of withdrawal"
Because international relations is reserved, Lord Keen says devolved parliaments "do not have a parallel legislative competence in relation to withdrawal from the EU". He seems very keen to hammer this point home, coming back to international relations issue repeatedly
Lord Keen says devolved parliaments have always had constraints on them, via schedule of reserved powers; Withdrawal Bill just "recasts" this for a post-Brexit world. Holyrood bill tries to "interpose" on that process.
"This is all potentially quite confusing," says Lord Reed.
Quite.
Quite.
Submissions at the Supreme Court in the matter of Holyrood's Brexit bill are complete, and judges are off to consider the "complicated" case.
"This definitely one for the wet towels, so we'll go away and apply them," says Lady Hale.
"This definitely one for the wet towels, so we'll go away and apply them," says Lady Hale.
