A senior Welsh Government minister has told MPs that his government can already be ordered to change the law in order to comply with an international trade deal.
Welsh Brexit Minister Jeremy Miles, who is both Brexit Minister and Counsel General, in charge of legal issues, appeared before MPs looking at the country's future relationship with the EU.
He told them that the power had never been used and would cause a constitutional row, which he thought the UK Government was trying to avoid through its Internal Markets Bill.
"That mechanism exists on the statute book already. It's never been used and it would be constitutionally very controversial if that were to happen".
"But the mechanism that the Internal Markets Bill provides, a backdoor mechanism effectively, wouldn't attract that level of attention, no doubt", he said.
Despite strong objections from Wales and Scotland, the UK Government is planning a system of mutual recognition of standards.
In the case of a devolved matter, like food safety, Westminster only passes laws for England but if chlorinated chicken, for example, was made legal in England, then it would have to be accepted in Wales, Scotland and Northern Ireland as well.
Both Mr Miles and his Scottish counterpart, Mike Russell, expressed a certain admiration for the way the UK Government was, as they saw it, undermining devolution.
The Welsh minister called it a "smartly drafted" bill, the Scottish minister described it as "sneaky".
Much of the row could be resolved if the UK and EU eventually reach a trade agreement covering food standards.
A poll for ITV Wales found that opinion was split about whether the talks should be extended if an agreement can't be reached by the December 31 deadline.
Overall, 39% favoured an extension but 31% would prefer no deal in those circumstances. The rest couldn't choose or didn't know.
But the picture was very different for those Welsh voters who backed the Conservatives at the 2019 General Election. 72% of them opted for no deal.