More than 11,000 employers fired at least one worker during a trial period in the first year of the Government's 90-day work trial law.
In 2011 all employers were given the right to dismiss new staff within 90 days without fear of being taken to court for unjustified dismissal.
Peter Conway of the Council of Trade Unions says too many people have been dismissed.
"If there were 11,200 employers that sacked somebody in their first 90 days, that could be a lot more than 11,200 workers if those employers do it more than once.
"And you would imagine that out of that number of people there would've been many workers who could've taken a personal grievance if they were covered by the law but for this 90 day trial period."
Pharmacy worker Heather Smith believes she was being used and felt small after her dismissal during her trial.
"All these questions like what did I do, what did I do wrong, when I know I didn't do anything wrong, but it is still in the back of your head, why have they done this?"
She challenged the decision in the High Court and won.
But chief executive of Business New Zealand, Phil O'Reilly, says the law gives people a better chance at employment, and it's actually working quite well.
"There is no publicity about this, there doesn't appear to be any great controversy about this, employers are simply getting on with it. The survey did suggest that people are hiring as a result of it, more than they might otherwise have, and particularly the evidence suggests that they are hiring people who might otherwise be at the margins of the workforce."
