THE idea of “devo-max” and a third option in a referendum on Scotland’s future has once again hit the headlines after the SNP’s former policy chief backed putting the idea to a public vote.

People from both sides of the political spectrum have expressed reservations about the move, with Unionist commentators calling it a "trap".

But what exactly is all the fuss about?

We asked politics guru Professor John Curtice to help talk us through some of the details of the devo-max debate.

WHAT IS DEVO-MAX?

Devo-max is an undefined term but is generally taken to refer to the possibility of full fiscal autonomy for Scotland. It has often been pushed as a “third way”, separate to the binary independence or bust offered by the 2014 referendum.

Under this full fiscal devo-max, Scotland would have maximum control over its finances, keeping all of the tax receipts raised in the country.

Instead of receiving a block grant from Westminster to fund devolved areas, Scotland would send cash to London in order to pay for reserved UK-wide services, such as defence and foreign relations.

However, exactly how this would work and which powers would remain reserved would need to be thrashed out in negotiations between Edinburgh and London. As such, the idea is a little muddied. Proponents of both the Union and independence have criticised devo-max, claiming “no-one knows what it is”.

READ MORE: Former SNP policy chief backs three-option referendum to break indyref 'logjam'

Curtice said: “The question that has to be answered by the people backing this idea is what further devolution powers do you think can be delivered within the framework of the United Kingdom.”

He said that the two “great limitations of the original settlement” - taxation and social security - have both been “breached” in the wake of the Smith Commission.

Writing in The National, the SNP’s former policy chief Chris Hanlon (below) outlined what he called “devo-min-max”. He said this term referred to the “smallest amount of increased devolution that those who support independence can live with”.

The National:

Hanlon made clear that he personally supports independence, but believes giving the people of Scotland a third option could help end the constitutional “logjam”.

However, his suggestion of giving Holyrood “supremacy” over devolved areas would clash with the UK’s foundational principle of parliamentary sovereignty, meaning no law can be created which Westminster cannot change. As such, devo-min-max seems unworkable.

WHAT IS PUBLIC OPINION OF THE IDEA?

Professor Curtice summed it up: “If you go back to polling around 2012/2013 and the debate ... about a form that the referendum should take when there was quite a substantial campaign in favour of devo-max, it was emerging in opinion polls at that time as the most popular option.

“Not any more.”

The idea of devo-max has fallen by the wayside after it was left off the 2014 ballot. Curtice said this had been done as the SNP did not want a safe half-measure to eat into Yes votes, while the Unionists sought a firm No to “kill the constitutional debate stone-dead”.

He said that while the idea of devo-max had been allowed to lapse, Scottish politics had become “deeply polarised”.

The National: Independence referendum 2014

“Recreating support for the idea of a bridge between [Yes and No] certainly looks like quite a considerable challenge … assuming you eventually manage to decide what it is, you’re really starting almost at base zero,” Curtice said.

Cautioning that polling was not comprehensive, the professor said that devo-max had come a clear third in surveys of the issue.

He said a YouGov poll in March had given it 21% support, versus 38% for independence and 28% for the current Union. A Panelbase poll in January 2021 had devo-max on 17%, with independence on 43%, and the current Union on 32%.

WOULD A THREE-OPTION BALLOT BENEFIT INDEPENDENCE OR UNIONISM?

On paper, the polling which includes devo-max as an option puts independence in first place.

The numbers show that more people who voted No support a devo-max option than people who voted Yes - around one in four vs one in 10. As such, Curtice agreed it would be fair to say that a third option on a referendum may hit the No side harder than the Yes side.

However, the professor was sceptical of such a vote being fair, saying it would be very difficult to organise “without creating a sense for people to vote tactically”.

“How do you possibly run a three-way referendum?” he asked.

He said a single transferable vote (STV) ballot, as suggested by Hanlon, would be the “closest you could get” to a fair system, but that it would end up depending heavily “on what comes second and what comes third” rather than a clear majority supporting the winning option.

THE ELEPHANT IN THE ROOM

Professor Curtice said that a “particular” issue facing proponents of devo-max is: “How does it address the question of Brexit?”

He went on: “The question of people’s attitudes towards independence now is quite closely tied with their attitudes towards Brexit. The majority of people who are in favour of independence want to join the European Union.

“How are they proposing to address that question?”

Even under devo-max, it is expected that control over foreign affairs would be reserved to Westminster. As such, Scots backing this third option would mean that a return to the European Union, much touted by SNP figures such as External Affair Secretary Angus Robertson, remains impossible.