Devolving justice to Wales would be a mistake of calamitous proportions, according to former Justice Secretary Sir Robert Buckland.
The Llanelli-born barrister said being part of the Wales and England jurisdiction was a good thing.
He was responding to a commission’s recommendations Wales take control of justice from Westminster as soon as possible.
The report has been given to the Welsh government to consider.
It said control over railways, policing and justice should be handed over but Sir Robert, who practised law in Wales, believed this would be a mistake.
“It would be a calamitous step for justice in Wales. We are as part of the jurisdiction of Wales and England, one of the most respected jurisdictions in the world,” he said.
“Our reputation for the rule of law, independence of our judges and our excellent legal profession as well, means that being part of a bigger entity is good for Wales.
“It’s good for the law in Wales, and I think it’s essential, frankly, that we stay as one jurisdiction. I utterly reject the idea that somehow we would be better off with a separate jurisdiction for Wales.”
The commission, co-chaired by former Archbishop of Canterbury Lord Williams and Cardiff University professor Laura McAllister, said there were three ways devolution could be developed.
It suggested an enhanced form with more powers, a federal system with the other UK nations, and full independence.
But it warned independence could mean economic hardship in the short to medium term.
Sir Robert said: “Independence is not viable. It’s all very well to put the word ‘viable’ in there, but look at what they say about short to medium term hardship.
“Do we really want to go down the road of 50 years of depopulation, an economy that is stagnating, and a country that frankly would be going backwards not forwards?
“Independence, I think, means penury for Wales, not success.”
The commission said it was not in its remit to recommend one course of action over another.
It was, it said, now up to politicians to decide whether to apply any of its suggestions.
Previously, First Minister Mark Drakeford called the report “a serious piece of work that deserves careful consideration and the Welsh government will be reviewing it in detail”.
Plaid Cymru called the report “ground-breaking” with party leader Rhun ap Iorwerth saying: “To have a report of this stature spelling out unambiguously that independence is a genuine option for us as a means to realise our potential is a very significant step.”
And Welsh Liberal Democrat leader Jane Dodds welcomed it for exploring “pragmatic ways” to reform Wales’ relationship with the rest of the UK.
- The topic will be explored further on Politics Wales at 10:00 GMT on BBC One Wales on Sunday.