The UK says it will consult the Scottish government on all changes to those policies, and try to seek agreement.
- How can it be the case that Westminster can introduce legislation against the will of the Scottish Parliament?
Finance Secretary Mark Drakeford - who has led Welsh negotiations on the bill - told AMs: "We have defended and entrenched our devolution settlement".
"It strikes me that if the UK Government decides after tomorrow to carry on regardless, it demonstrates we were right not to take some of this on trust", she noted.
"These plans have been backed by the Labour Government in Wales".
But Plaid Cymru AMs were vocal in their opposition.
The problem is that clause 15 of that bill automatically transfers those new powers to Whitehall.
The Scottish parliament's approval is not legally necessary for the bill to become law, as Westminster can disregard Holyrood, but such a move would provoke the biggest political rift between the two institutions since devolution in 1999.
Plaid AM Adam Price said: "We are joining a very select club of national Parliaments, if we pass this motion today, that have voluntarily chose to cede their own authority".
The Scottish government has urged the Parliament in Edinburgh to refuse "legislative consent" for the highly contested EU (Withdrawal) Bill now being debated by lawmakers in London.
Members of the Scottish National Party, the Labor Party, the Liberal Democrats and Scottish Greens showed a rare unity, approving the proposal of the Scottish government to reject the European Union withdrawal bill.
European Union negotiators have rejected both options and Conservative Brexiteers have criticised the prime minister's favoured option of a customs partnership as unworkable and inconsistent with regaining full sovereignty from Brussels.
If no deal between Edinburgh and London can be reached, Westminster has the option of introducing the Withdrawal Bill against the wishes of the Scottish Parliament.
"The mechanism for us is not really the issue, it's the issue of the consent of the parliament".
- What is legislative consent and why does it matter anyway? However even if Holyrood votes to refuse consent, Westminster can still go ahead and introduce the legislation anyway.