Today marks the first official test of newly-elected Labour leader Jeremy Corbyn, as he takes part in his first parliamentary showdown from the frontbench.
On the agenda: the Trade Union Bill, a package of proposals put forward by the government that would change the rules surrounding strike ballots.
Business secretary Sajid Javid, who is opening the debate for the government, has said that the new law will "stop the ‘endless’ threat of strike action hanging over hardworking people".
But Corbyn has called the bill "pernicious", saying it amounts to little more than an attack on the unions.
Writing in the Observer yesterday the new Labour leader slammed the TUB, saying it would “make it harder for workers to get a fair deal at work, to fight for fair pay and for a better work-life balance”.
“Trade unions are a force for good – a force for a more equal society,” he added. “United, Labour will vote against this anti-democratic attack on trade union members.”
And union bosses - many of whom have openly supported Corbyn in his successful bid to become the leader of the opposition - have threatened to "topple the government" if the government reforms go ahead.
Among the reforms the government is suggesting: a 50 per cent threshold for ballot turn-out in all industrial action votes, and an additional 40 per cent threshold of support to take industrial action in protected sectors like health, education, fire, transport and border security.