Quebec's firefighters are heading to court in an attempt to have a provincial law altering pension plans declared unconstitutional.

On Wednesday the Union of Quebec firefighters (SPQ-FTQ) is filing court documents to overturn a pension reform law which came into effect in Dec. 2014. That law, among other requirements, gives provincial ministers the power to order changes to municipal pension plans that are underfunded.

The lawsuit being filed targets the Attorney General of Quebec, Minister Sam Hamad, and the cities of Levis, Saguenay, St. Jerome and Sherbrooke.

Daniel Pepin of the SPQ-FTQ believes the provincial government wants to tear up contract agreements where pension plan payments where fairly negotiated.

The Union will argue that law 15 violates the Charter rights to freedom of association, and that the law's true goal is not to fully fund pension plans, but instead to reduce the salaries of municipal employees.

The provincial government justifies the pension reform laws by saying that municipal pension plans are severely underfunded.

In April a coalition of police forces also launched a court challenge to Bill 3, in what it expected would be a six-year battle heading to the Supreme Court of Canada.

With files from The Canadian Press