The Alberta Union of Provincial Employees claims that the law violates the charter rights of workers to act collectively and also breaches their rights to liberty and security.
The lawsuit asks a judge to reinstate the union's right to binding arbitration and to make the province reimburse workers for wages the union believes they would lose.
The imposed four-year contract kicks in at the end of January unless the province and the union work out a deal.
It would freeze wages in the first two years and give one per cent increases in each of the following two years.
Premier Alison Redford has said the law was necessary to ensure that public sector wages stay in line with wage restraints faced by teachers and doctors.
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