The Scottish Labour leader Kezia Dugdale has made what she hopes is a major speech to win back lost voters and make her party relevant in the constitutional debate that has followed the Brexit vote in the EU referendum.

In an address to the Institute for Public Policy Research think tank in London, she called for a federal UK founded on a “new Act of Union” that included repatriating to Scotland the EU’s powers in areas like fisheries, farming and employment rights. This would come on the back of a constitutional convention for the UK to determine what form a new settlement should take, modelled on the deliberations in Scotland that culminated in the opening of the Scottish parliament in 1999.

Dugdale’s proposal aims to save the union from what she sees as a UK Tory government and Scottish SNP government both intent on pulling it apart – albeit even some notable Labour figures such as former first minister Henry McLeish have said they would back a Yes vote in a second Scottish independence referendum. Dugdale said:

We are now faced with a Tory government in Westminster which looks set to force hard Brexit on the whole of the UK. And an SNP government at Holyrood which wants to exploit the divisions to win independence. This is the position that the majority of Scots – the moderate, pro-union Scots and also many former Yes voters – find themselves in.

Echoes and errors

Dugdale’s speech does not break very new ground. It echoes recent calls by Gordon Brown, the former UK prime minister, for a federal UK devised through a constitutional convention with an elected senate and greater powers for Scotland.

Meanwhile, the idea of a new Act of Union to replace the 1707 original has been floated in the past by Dennis Canavan, the then maverick Labour MP who later became chair of Yes Scotland for the 2014 independence referendum; and more recently by the likes of former Lib Dem leader Menzies Campbell and former Labour Welsh Secretary Peter Hain.

That aside, Dugdale has made the mistake of trying to deal with the UK constitution and Scotland’s future/Holyrood powers at the same time. That is not to say there is not an opportunity for Labour on the constitution. The SNP is currently the party of independence but by default also the party of Home Rule.

The SNP has the problem that support for independence is strong enough to keep the party in office but too low to make it confident of securing its ultimate goal. This explains why the party has not taken a hard line against a settlement short of independence. Former first minister Alex Salmond attempted to get devo max on the 2014 ballot, for example, while his successor, Nicola Sturgeon, accepted the Smith Commission devolution proposals while demanding more autonomy at the same time.

Some in Labour recognise that they cannot out-unionist the Scottish Conservative and Unionist Party and need to carve out a role for themselves as a Home Rule party. Alex Rowley, Dugdale’s deputy, has sought to do this, arguing, for example, that Labour should have campaigned for Home Rule in the run-up to the Holyrood elections in May.

Dugdale is coming late to the party and calling for something that would not go as far as Home Rule, and still seems trapped in a Labour unionist mindset that sees Westminster as being the only possible driver of change. Calling for new powers is all very well, but her proposal is still subject to winning the backing of the UK Labour party and then waiting for a Labour government at Westminster that can implement it.

The rather obvious question for Labour is, why not seek these repatriated EU powers through gaining a mandate at Holyrood? Westminster recognised the SNP 2011 victory as a mandate to negotiate an independence referendum. If Labour and any other parties won a Holyrood mandate for Home Rule, would that not mean that Westminster would have to negotiate a further extension of powers?

By focusing on federalism, on the other hand, Dugdale is calling for something that requires a UK-wide mandate and for which it has to be debatable whether support exists in England. There has not been enough support for English regional parliaments to get them off the ground in the past, for example.

At the same time, I question whether repatriating powers from the EU to Scotland would really require a UK-wide convention. In what sense does the UK’s relationship with its constituent parts need to be resolved before Scottish Labour could, for instance, argue for EU employment powers to be repatriated to Holyrood?

How to live dangerously

Had Dugdale effectively started a campaign for a Scottish Home Rule mandate and repatriating EU powers to Scotland, she could have carved out a distinct position on the constitution while still supporting a final federal destination. It would at least have allowed Labour to appear relevant on the constitution in future Scottish elections.

If the SNP government is able to gain new powers from Brexit, it would mean Scottish Labour could more legitimately take some credit. On the other hand, if the Scottish government fails to achieve this or gain enough support for a second independence referendum, Labour could claim to have a credible alternative that voters can support in a Scottish election.

Instead, Dugdale has allowed the SNP to maintain its constitutional coalition of independence voters and those who want more powers but would settle for less. The former will undoubtedly stay with the SNP while the latter have not been offered an alternative.

When the former Labour first minister Donald Dewar signed up for a Scottish constitutional convention in 1989, he said it had become necessary for Scots to live a little dangerously. Scottish Labour would do well to heed the advice of their most successful leader since the founding of Holyrood and take a similarly bold approach.