Wales could gain new powers over parts of the criminal justice system if Labour forms the next UK Government.
The party has published a report it commissioned by the former Prime Minister Gordon Brown, into the way the United Kingdom is organised in the future.
Its main recommendation is abolishing the House of Lords.
Welsh Labour leader Mark Drakeford said: “This report puts forward important ideas about how power can be devolved and shared throughout the country to create a stronger union and a stronger United Kingdom.”
But the report has been criticised as a “damp squib” by Plaid Cymru.
The document will form the basis of Labour’s policies for the next UK election, expected in 2024 or 2025.
Party leader, Keir Starmer, said it was “the biggest ever transfer of power from Westminster to the British people.”
Among Gordon Brown’s recommendations is the proposal that Wales is given new powers over youth justice and probation.
Such a move would be part-way towards delivering Welsh Labour’s pledge to pursue the transfer of the entire criminal justice system, replacing the current England and Wales system.
The report also calls for the devolution settlement to be protected in law, to prevent future UK Governments from altering it.
It says that Senedd Members should be allowed the same privileges and protections that MPs enjoy for what they say in the Senedd chamber.
There should also be what it calls “enhanced access to economic resources for Wales” utilising the British Regional Investment Bank.
And the panel says there should be a new system to bring together the devolved leaders with senior UK ministers under a council led by the Prime Minister.
However the report leaves the detail of which new powers should be transferred to Wales until the publication of an Independent Commission, led by Professor Laura McAllister and former Archbishop of Canterbury, Dr Rowan Williams.
It says, “In Wales, our proposals strengthen self-government for a new era, but we are mindful that the Welsh Government has set up an independent Commission to make recommendations on constitutional issues.
“We know that we can rely on the Welsh Labour Government to publish its Plan for Wales that employs to the full the powers of the Senedd and, at the same time, maximises the benefits from co-operation across the United Kingdom.”
The commission led by Gordon Brown also proposes replacing the House of Lords with a “smaller, more representative and democratic” assembly of the nations and regions, although details would be matters for further consultation.
The panel proposes new rules for politicians and civil servants, clamping down on MPs’ second jobs and creating a “powerful” anti-corruption commissioner to root out criminal behaviour in British political life.
Scotland would also gain enhanced powers under the proposals, being able to enter into international agreements in relation to devolved matters.
Welsh Labour leader and First Minister, Mark Drakeford welcomed the report.
He said, “The union of the United Kingdom is under greater threat now than at any other time in its long history as a result of the actions – and neglect – of successive UK Conservative Governments.
“I want to thank Gordon Brown for all the work he has put into this timely, comprehensive report and set of recommendations for the future of the UK. I am very grateful for the engagement we have had during the development of this report.
“Labour is the party of devolution and this report shows that only Labour is thinking urgently about the future of the United Kingdom. This report puts forward important ideas about how power can be devolved and shared throughout the country to create a stronger union and a stronger United Kingdom.
"I look forward to seeing these recommendations realised as soon as we have a Labour UK Government.”
Labour’s frontbencher in parliament for Wales, the Shadow Welsh Secretary, Jo Stevens echoed his comments.
She said, “I’d like to thank First Minister Mark Drakeford, former First Minister Carwyn Jones and Baron Murphy of Torfaen for their work on Gordon Brown’s Commission that has resulted in the report and recommendations published today.
“As Keir Starmer has said, we will now consult widely on the recommendations as they form part of our wider plan to build an economy in which growth is created by and for everyone everywhere.”
However Plaid Cymru’s Parliamentary leader Liz Saville Roberts has condemned the panel’s recommendations, saying: “This report is a damp squib for Wales.”
She added that, “By offering more powers to Scotland than to Wales, Labour is once again showing that how much they are in awe of SNP-run Scotland while taking Labour-run Wales for granted. Scotland is rewarded while Labour is content for Wales to make-do and mend with piecemeal powers.
“Not only does this report not go far enough, but it also backtracks from previous Labour promises – the 2017 Labour manifesto having promised the devolution of policing to Wales.
“The Labour Welsh Government’s Thomas Commission recommended that justice should be wholly devolved, and a Welsh legal jurisdiction created. This timid report only offers piecemeal powers over youth justice and probation, showing the level of disdain the central Labour party holds towards the only government it currently runs.”
And she concluded by saying that, “Despite Labour claiming this is the biggest transfer of power away from Westminster, it is clearly not to the people of Wales.”
The Welsh Conservatives have strongly criticised what they say is an "obsession with constitutional tinkering."
Shadow Constitution Minister, Darren Millar, said, “There is no great public appetite in Wales for further powers to be devolved to the Senedd.
“Wales already has the powers it needs to deliver a better economy, better schools and better hospitals, but sadly the Labour Party has spectacularly failed to use them to achieve those aims. “Instead of its obsession with constitutional tinkering, the Labour Party should be using the existing powers it has to improve the lives of the people of Wales.”
Welsh Liberal Democrat leader, Jane Dodds, says the report makes "Wales feel like nothing but a sidenote" adding that it "also appears to follow a long-running pattern of giving Scotland more powers than Wales.
“In particular, the recommendation on devolving youth justice to Wales actually falls short of the Silk Report from 2011, which recommended devolving policing and looking at criminal justice. In this regard, Labour seemed to have moved backwards.
“Another crucial element not present is the devolution of borrowing powers, vital if Wales is to be able to build the infrastructure our economy needs to thrive.”
“Finally, the elephant in the room is once again missing. If we are to build a truly fair and equal democratic system in the UK, that means ditching first past the post elections in Westminster and bringing in proportional representation, something which Labour has again missed out. "