The Smith proposals are radical: the devolution of extensive tax and welfare powers will make Scotland one of the most autonomous regions in western Europe.
But only a federal system can manage these changes while also giving Scotland a continuing stake in the Union. Otherwise, as the Scottish Parliament gets stronger, the UK may appear more irrelevant to many Scots. Federalism may well be the last throw of the dice for the Union.
Federalism is a flexible term, indicating a balance between self-rule and shared rule. UK devolution has been about self-rule for Scotland, Wales and Northern Ireland rather than their shared role in UK decision making. This representation deficit needs to be addressed.
A move to English regions may be needed. Additionally, the West Lothian question – that Scottish MPs vote at Westminster on matters affecting only England – cannot now be avoided. This need not mean an English Parliament but will need restrictions on Scottish MPs.
There is also the status of the Scottish Parliament. In theory Westminster could abolish it altogether. Smith proposes that the Scottish Parliament be made permanent. This would presumably also extend to protecting its powers. This is a radical proposal which will change Westminster’s sovereignty.
Another change not mentioned by Smith, but argued for by Gordon Brown, is turning the House of Lords into a chamber of the nations and regions. This could offer a genuinely union-focused institution at the heart of the UK. Scots also need a say in the making of central government decisions which affect Scotland – this would give Scots a better sense the UK works for them.
We can’t tell if a move towards a federal UK will give the Yes Scots a sense of belonging, but without broader reforms the Smith process may further unsettle the union it was intended to save.
• Professor Stephen Tierney is a Fellow of the Centre on Constitutional Change and professor of constitutional theory at Edinburgh University.