Parliament has passed the Government's controversial Employment Relations Amendment Bill.
It passed its final reading 62 votes to 58.
The legislation makes extensive changes to collective agreements, the 90-day trial period, strike action, and rest and meal breaks.
The Labour Party claims it effectively scraps teabreak entitlements, affecting hundreds of thousands of workers.
However, Workplace Relations Minister Michael Woodhouse told the House that description was wrong and had created a climate of fear.
"The very workers they claim to represent, and for that the Opposition should be ashamed."
Mr Woodhouse said the new law would give employers greater confidence to compete and expand.
The Government's support partner, the Maori Party, voted against the legislation.
Maori Party MP Marama Fox told the House the changes were not about the people.
"By allowing bosses to walk away from collective agreements, the new law introduces the right for employers to opt out of multi-employer collective bargaining," she said.
"While we welcome the new measure which requires employers to have first acted in good faith, it is the fact that the principle of collective bargaining is threatened which we are particularly concerned about."