A federalism expert has questioned whether the UK could adopt the system in response to the on-going constitutional debate in Scotland.
Dr Wilfried Swenden, a senior politics lecturer at the University of Edinburgh, said if such a system was to be adopted several complex political issues would first need resolved.
Of the world’s functioning democracies, more than half of the total population live under federal structures. Global giants such as the US, Canada, Germany and India all have established forms of government which divide powers between a central parliament and territorial entities.
As Scotland, Wales and Northern Ireland make up just 15 per cent of the UK’s population, Dr Swenden said there was some doubt whether Westminster would allow its ultimate sovereignty to be shared.
Under federalism, regional assemblies legislate on everything from law enforcement to taxation - but typically they retain some form of veto against central government decisions that could impact on them.
“Would the UK Government be willing to give a veto right to Scotland, Wales and Northern Ireland? The logic of federalism would say yes,” said Dr Swenden.
“If the UK was a truly federal multi-nation state, it would somehow have to accept that some decisions are subject to the consent of not just a popular majority, but a majority of the nations that constitute the UK.
“But geographically, this is difficult. I think one of the weaknesses of the UK set-up is the absence of regional governments in England or the absence of an English parliament.”
Yet the appeal of federalism remains strong. Kezia Dugdale, Gordon Brown and Kenny MacAskill are just some of the senior politicians to raise the idea of Scotland gaining extensive powers while remaining part of the UK under a new federalist structure.
MacAskill, a former SNP minister, wrote in a newspaper column this week that federalism offered “a potential route forward for unionists to improve the constitutional settlement and for nationalists to maintain the dream.”
But the UK lacks many of the “essentials” of federalism, such as a constitutional court which could police differences between the centre and the territories, as happens in the US under the Supreme Court.
“One of the problems in the UK is there is no fixed guarantee the autonomy which is given to the devolved entities is secure,” said Dr Swenden.
“Westminster would not normally legislate on devolved Scottish matters without the consent of the Scottish Parliament - but is this always going to be the case?
“When the UK Government suspended the Northern Irish Assembly for a period, as the power-sharing agreement was not working adequately, it showed it is possible in a non-federal settlement for the centre to interfere with the entities.
“Parliamentary sovereignty does not yet make it possible for a UK bill to be struck down by the Supreme Court if it were to violate, for example, the Scotland Act. In a federal set-up, it would be possible to strike down Scottish Parliament acts but equally the UK Parliament as well.
“The Scotland Act, which devolves powers to Holyrood, is only an ordinary bill - even though we may give it de facto constitutional status.”
The UK’s lack of a written constitution and the relative weakness of the House of Lords are other stumbling blocks.
“Normally, in a federal set-up, there are mechanisms which allow the collective input of territorial entities on decisions which the centre takes which have a bearing of them,” continued Dr Swenden.
“This is often done through a second chamber - in Germany, you have the Bundesrat, where certain federal bills passed in the lower chamber cannot be approved without its concurrent consent.
“The House of Lords is relatively weak in comparison and in its current composition is in no way reflective of the territorial make-up of the UK.”