Unions have criticised research showing the Government's 90-day probation period has led to more jobs.
The Institute of Economic Research published a study on 2 February claiming to show that the new law led to more hirings and improved market flexibility.
But the Council of Trade Unions has taken issue with the institute's findings, saying the firms it studied were not necessarily using the 90-day trial.
The union also claims the institute's analysis was flawed.
CTU economist Bill Rosenberg says the report lacks validity and there is no basis for the institute and the Department of Labour to present these findings as evidence that the new law has created more jobs.