Twelve federal public service unions have filed a legal challenge to the budget bill passed earlier this year — and the country's largest such union plans to file its own challenge Tuesday — arguing that the bill's plan to save $900 million by overhauling sick leave and disability programs violates the country's Charter of Rights and Freedoms.

The budget bill was passed in April, and its proposed changes to federal civil servants' sick leave provisions are one of the most contentious issues in talks with public service unions.

Those talks were temporarily stalled in May when the Public Service Alliance of Canada walked away from bargaining meetings, but Bill C-59 would give the government the ability to act before the conclusion of that process, something unions argue contravenes the Public Service Labour Relations Act.

"In our view, the portion of this legislation dealing with sick leave bargaining is unconstitutional," said a media release issued Monday by the Professional Institute of the Public Service of Canada, one of the 12 unions that filed Monday's challenge.

"It fundamentally undermines the constitutionally protected process of collective bargaining and the right to strike."

The $900 million in savings expected with the changes to sick leave was a major piece of Finance Minister Joe Oliver's framework for reaching a $1.4-billion budget surplus for 2015-16.

The budget also said reducing long-term disability costs and other savings from unwinding the liability related to sick leave would result in savings of $200 million in 2016-17 and 2017-18 and $100 million in the following two years.

Canada's largest public sector union, the Public Service Alliance of Canada, confirmed Monday evening that it plans to file its challenge on Tuesday.

"The Supreme Court has confirmed that the right to collective bargaining is a protected right under the charter and we are defending that right through all legal means at our disposal," said Robyn Benson, PSAC's national president, in a media release.

Read the full legal challenge filed Monday below.

Bill C-59 challenge filed by 12 federal public service unions

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