The Scottish Government has introduced new legislation aimed at protecting Holyrood's powers from the "unfolding disaster of Brexit" - despite the Presiding Officer ruling the Bill is not legislatively competent.
Ken Macintosh said after "careful reflection" he had come to the conclusion the Continuity Bill "would not be within the legislative competence of the Parliament".
It is the first time Scottish ministers have brought forward a bill the Presiding Officer has ruled to be outside Parliament's legislative competence.
Brexit Minister Mike Russell said he regretted the need to introduce the UK Withdrawal from the European Union (Legal Continuity) (Scotland) Bill - but insisted it was "essential preparation" for leaving the European Union.
It will be rushed through Holyrood on an emergency timetable - with Mr Russell saying it would be for MSPs as a whole to decide if the Bill should pass.
He stated: "All MSPs can listen to the arguments and then collectively we can all decide if this Bill should become law.
"It will be a decision not of the Scottish Government but of this, our national Parliament, and that is how it should be and that is why we are bringing forward this Bill."
It comes as talks between London and the devolved administrations over the UK Government's European Union (Withdrawal) Bill remain deadlocked - with both Scotland and Wales branding the proposals a "power grab" which would undermine devolution.
Mr Russell said: "Article 50 has been triggered, without a drastic change of circumstances, which many of us still hope for, regrettably it is more than likely that the UK is leaving the EU. This Bill is a necessary response to that fact.
"This is the first time since the reconvening of the Scottish Parliament in 1999 that the government has introduced a bill and the Presiding Officer has not been satisfied as to the legislative competence.
"We recognise that, we are mindful of what a serious moment it is."
But he said Scotland's top law officer, Lord Advocate James Wolffe QC, was "satisfied that the Bill is within the legislative competence of the Parliament".
Mr Russell added: "The Presiding Officer's statement on legislative competence does not in any circumstance prevent the Scottish Government from introducing or progressing any bill.
"By triggering Article 50 the UK Government has put the UK on a path which leads of the European Union. As I have set out we have a duty to protect and preserve those areas of EU law that are within the responsibility of this Parliament."
The dispute with the UK Government centres over where powers should go when they return from Brussels, with SNP ministers saying all devolved powers currently exercised there should come straight to Holyrood.
Westminster however argue responsibility for some areas must go to London first, to allow common frameworks to be set up across the UK.
Conservative constitution spokesman Adam Tomkins described the Scottish Government's decision to bring forward the Bill as "unwelcome and unnecessary".
The Tory MSP said: "Up until now there has been a constructive approach from both the UK and Scottish governments.
"The fix to make this process fit for purpose is within reach. But the SNP must now reflect on whether this move will help or hinder the process."
But Labour's Brexit spokesman Neil Findlay blamed Scottish Secretary David Mundell and Scottish Conservative leader Ruth Davidson for the latest developments, saying the Tories had failed "to deliver on commitments given to resolve issues around the devolution of powers coming from the EU".
Scottish Greens co-convener Patrick Harvie said: "The introduction of this bill is an absolutely necessary response to the Brexit crisis and to its incompetent mishandling by a UK Government."
Lib Dem Tavish Scott said the failure to reach agreement on the EU Withdrawal Bill was "not good".
"It is also not satisfactory that we have no legal agreement on this Continuity Bill," he added.
Mr Mundell said: "We have been clear that we will protect and enhance the devolution settlement as we leave the EU, and that there will be a significant increase in Holyrood's decision-making powers.
"But it is crucial we protect the UK's valuable common market, and to do so we will need common approaches across the UK in some areas.
"We have made a considerable offer to the devolved administrations on amending the EU (Withdrawal) Bill, and look forward to further constructive talks."