The DUP's Sammy Wilson was one of just two non-Tory MPs to vote for the UK government's controversial new legislation to restrict strikes.
The bill would require "minimum service levels" during public sector strikes, but trade unions have condemned the plan as "undemocratic, unworkable and illegal".
It cleared its first hurdle in Parliament this week with 309 MPs to 249, a majority of 60, voting to give the bill a second reading.
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Details of the minimum service levels which would need to be maintained during strikes have yet to be set out, and the government says it will consult on this.
Only Mr Wilson and an independent MP joined Conservative MPs in supporting the Strikes (Minimum Service Levels) Bill.
DUP MP Jim Shannon, SDLP leader Colum Eastwood and MP Claire Hanna, and Alliance deputy leader Stephen Farry voted against the legislation.
Mr Eastwood described the bill as "anti-worker" and "anti-union".
He said: "The SDLP stands squarely behind workers and their right to strike.
"It is time that essential workers who have been forced into striking by this Tory government are given the fair pay and working conditions they deserve.
"SDLP MPs will fight this anti-worker, anti-union bill and oppose it at every opportunity."
Jemma Dolan, Sinn Fein's spokesperson on workers' rights, said the bill would "fundamentally undermine workers' rights".
The Fermanagh and South Tyrone MLA added: "Employment is devolved to the Assembly and a priority for Sinn Féin in a new Executive will be to protect workers' rights by implementing the New Decade New Approach commitments on employment and strengthen collective bargaining rights.
"It is clear the Tories are bad for the economy and bad for workers. We need an Executive formed immediately to help support people and businesses through the cost of living and growing income crises."
The DUP was approached for comment.
As the bill was considered on Monday evening, Business Secretary Grant Shapps told MPs the public "has had enough of the constant, most unwelcome, frankly dangerous, disruption to their lives" amid a wave of strikes.
He said: "There comes a time when we can't let this continue and that is why we need minimum safety and service levels – to keep livelihoods and lives safe, and it's frankly irresponsible, even surprising, for the opposition opposite to suggest otherwise."
But Labour deputy leader Angela Rayner criticised the bill as "indefensible and foolish", adding: "It threatens teachers and nurses with the sack during a recruitment and retention crisis."
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