The SDLP has labelled the legislation an attack on devolution
Politicians in the UK are expected to vote on the first key piece of Brexit legislation at Westminster later tonight.
The 'EU Withdrawal Bill' would end the supremacy of EU law in the UK.
British Prime Minister Theresa May has said she is “confident” of winning the vote which has been debated throughout the day.
Her government has warned that voting against the Bill would result in the UK suffering a “chaotic” EU exit.
A Downing street spokesperson said: We've said this is a hugely important bill in terms of preparing the way for a smooth Brexit for business and the rest of the country, and we encourage all MPs to support it."
The vote is expected to take place either later tonight or in the early hours of tomorrow morning.
The bill overturns the 1972 Act which took Britain into the European Economic Community (EEC).
In doing so, it incorporates EU laws onto the UK statute book in an effort to prevent loopholes in the law following Brexit.
The British Labour Party will vote against the legislation, mainly because it objects to so-called Henry VIII powers, which are named after a statutory instrument used by the Tudor king to force through new laws without full parliamentary scrutiny.
Labour says these powers in the bill amount to a "power grab", but the party has rejected accusations it is trying to derail the Brexit process.
Speaking to Sky News, shadow Brexit minister Jenny Chapman said: "Labour will not block Brexit."
"If you disagree with anything the Government does on Brexit, you are a Brexit betrayer," she said.
"Our position is about this being a very bad bill - it's bad for our democracy, it doesn't enable Parliament to take back control the way that people want, and crucially it gives ministers these powers that they just don't need for Brexit."
However, about a dozen Labour MPs from Leave-backing constituencies could rebel against Jeremy Corbyn's orders.
Mrs May, whose majority in the Commons relies on a deal with the DUP after the Conservatives' poor showing at the last General Election, also faces a potential rebellion.
Several Tory MPs have said they are unhappy with the bill, with former attorney general Dominic Grieve describing it as "an astonishing monstrosity."
They are expected to vote for it for now and seek amendments in the future, which could leave the minority Government having to make concessions to avoid defeat.
In the North, the SDLP leader Colum Eastwood labelled the legislation a “power grab that devalues the principles of devolution” and urged MPs from all parties to oppose it.
“For months, we have been constructively attempting to restore devolution in Northern Ireland with the primary focus of mitigating the impact of Brexit on people here,” he said.
“And now, the British Government sees fit to introduce legislation that will disempower devolved administrations, centralising power with a cabinet of Brexiteers, free from scrutiny or accountability. That is unacceptable.”
He noted that the Bill can only pass with the support of the DUP - warning that “they have a decision to make today.”
“Will they take a stand for people in Northern Ireland or will they bend the knee to David Davis and Boris Johnson, giving away more of our hard fought for powers to this Tory government?” he asked.
He also lashed out at Sinn Féin for its policy of not taking up seats in Westminster warning that the vote will “again reflect the absence of the voice of Irish nationalism from Westminster.”
He called it a “critical vote, on a knife edge that will have a profound impact on the people of this island” adding that “our community is silenced.”
The British Government rejected claims the legislation amounted to a power grab.
It said the bill is necessary to ensure stability and continuity to businesses and citizens when Britain's EU membership ends in March 2019.
Ahead of the debate, Brexit Secretary David Davis said: "A vote against this bill is a vote for a chaotic exit from the European Union.
"Without it, we would be approaching a cliff edge of uncertainty which is not in the interest of anyone."
Additional reporting from IRN ...