It will be the first time any aspect of the Scottish Government’s official position on the legality of indyref2 will be made public and follows a 13-month transparency battle.
In a ruling, Scottish Information Commissioner Daren Fitzhenry said the Government’s decisions during the Alex Salmond inquiry and the “obvious” and “significant” public interest around a second independence referendum meant parts of the legal advice should be released.
Critics said the “devastating rebuke” to ministers was another example of the “secretive SNP Government” attempting to “stifle scrutiny”.
They said continuing to pursue a referendum after being told plans would not stand up in court could equate to a “significant abuse of public funds”.
Nicola Sturgeon has repeatedly said she will pass legislation in Holyrood allowing for a second independence referendum to take place by the end of 2023.
However, constitutional lawyers are split over whether the Scottish Parliament has the power to pass such legislation, with many believing any referendum bill will end up in a protracted legal battle between the UK and Scottish governments, played out in the courts.
Ministers have also faced accusations of planning to push ahead with a potential referendum held without the agreement of Westminster.
Such a vote would likely spark a boycott of the vote by unionist parties.
Ministers must now disclose parts of the legal advice by June 10, the decision notice states.
It is the latest transparency defeat for the Scottish Government after The Scotsman also forced ministers to reveal the scale of care home and hospital deaths to Covid-19 in individual institutions, as well as publish secret modelling of a then potential second wave of the virus. The Government was also found to have unlawfully claimed its own report into harassment complaints against Mr Salmond did not exist.
Ministers have separately faced intense pressure over secrecy due to the ongoing ferries fiasco, which has seen two vessels, hulls 801 and 802, run two-and-a-half times over budget and five years late.
A scathing Audit Scotland report concluded that reasons for a key ministerial decision had not been recorded. The Auditor General told MSPs last week it was “fair” to suggest ministers may have broken the law by not recording a key ministerial direction when awarding the contract for two ferries to Ferguson Marine.
Before the election in May last year, the SNP was also forced to release legal advice relating to their doomed defence against the judicial review brought by the former first minister, Mr Salmond, only doing so after the threat of a no-confidence motion in deputy first minister John Swinney.
This decision, Mr Fitzhenry said, demonstrated ministers recognised there could be “compelling public interest reasons for disclosure of legal advice”.
He concluded aspects of the legal advice on indyref2 would fall under the same “exceptional circumstances” in which public interest outweighed legal professional privilege.
The Government had been initially asked for any legal advice to ministers or provided by the civil service on the topic of a second independence referendum during the year 2020.
Officials refused to release any information, claiming disclosure would breach legal professional privilege – a convention that ensures confidentiality of legal advice.
In his ruling, Mr Fitzhenry accepted the “considerable, in-built public interest” in allowing ministers to receive “full unhindered legal advice”.
However, he agreed with submissions from The Scotsman this was “not inalienable”, adding the Scottish Ministerial Code sets out there are exceptions to this convention, including when the legal advice may affect a “large number of people”.
Mr Fitzhenry wrote: "The Commissioner notes the applicant’s view that keeping legal advice relating to a second independence referendum secret actively harms accountability and scrutiny and would be counter to the public interest.
"Given the fundamental importance of Scotland’s future constitutional relationship to all individuals living in Scotland, and its fundamental importance to political and public debate at the time of the request and requirement for review, the Commissioner is satisfied that disclosing this information would significantly enhance public debate on this issue.
"While the ministers have expressed concern that disclosure of legal advice in this case would have the effect of future legal advice being more circumspect or less effective, the Commissioner acknowledges the point made by the applicant that the ministers’ own decision to disclose legal advice relating to the Alex Salmond case has already created such an environment, if the risk were there, and a further disclosure of legal advice which is of much greater public interest is unlikely to create any further difficulty.”
Douglas Ross, leader of the Scottish Conservatives, said this “devastating rebuke” was the latest in a long line of scandals, referencing the non-disclosure agreements with Ferguson Marine staff and the “conveniently missing” documents around the ferry contract award.
He said: “This is a devastating rebuke to the unacceptable culture of secrecy at the top of the SNP Government.
“The advice given to ministers on the legal validity of a second independence referendum is demonstrably in the public interest and the Information Commissioner is right to rule that withholding it was unlawful.
“If the SNP are going to devote large sums of public money deploying civil servants to work on a divisive referendum that the majority of Scots don’t want, we are entitled to know the legal advice they have been given.
“The failed attempt by Nicola Sturgeon and Co to hush this up is just the latest example of a Government prepared to go to any lengths to avoid scrutiny.”
Sarah Boyack, the constitution spokesperson for Scottish Labour, said: “This ruling is a another rebuke for this secretive SNP Government, who’ve been caught once again trying to withhold information and stifle scrutiny.
“The public have a right to see this information about their future and the SNP must release it right away, but more importantly they must stop wasting time, energy and money on this separatist distraction.
“People in Scotland need their Government to be focused on recovering from the pandemic and tackling the cost-of-living crisis – not tying themselves in legal knots in an attempt to hide the holes in their case for a divisive referendum.”
Willie Rennie, the former leader of the Scottish Liberal Democrats, said backing an independence referendum against legal advice would be a “significant abuse of public funds”.
He said: “This is a victory for transparency in the face of a Scottish Government whose default setting is to flout the Freedom of Information Act and throw up road block after road block.
"Anyone who has regularly submitted Freedom of Information requests knows that the Scottish Government has an arsenal of dirty tricks that it falls back on.
"If ministers have been wasting public money on preparing plans for another separation referendum despite being told that their indyref2 plans wouldn't stand up in court, then that would be a significant abuse of public funds."
The Scottish Government spokesperson said:
A Scottish Government spokesperson said: “We have received the decision from the Scottish Information Commissioner and are considering its terms.
“However, we are clear the Scottish Government has acted lawfully in its application of freedom of information legislation.
“There is a long-standing convention, observed by UK Governments and Scottish Governments, that government does not disclose legal advice, including whether Law Officers have or have not advised on any matter, except in exceptional circumstances.
“The content of any such advice is confidential and subject to legal professional privilege. This ensures that full and frank legal advice can be given.”