By David Ljunggren and Anna Mehler Paperny

OTTAWA (Reuters) – The union representing workers at Canada’s two main rail companies announced on Friday that it has filed court challenges against rulings by the country’s industrial labor board that mandated their return to work.

On Saturday, the board accepted a request from the government to order over 9,000 Teamsters members back to work at Canadian National Railway (TSX:CNR) and Canadian Pacific (NYSE:CP) Kansas City, and to impose binding arbitration.

The union argued it would appeal the rulings, stating they favored the railways and could undermine workers’ bargaining power.

“These decisions, if left unchallenged, set a dangerous precedent where a single politician can dismantle a union at will,” said Paul Boucher, president of the Teamsters rail union.

“The right to collectively bargain is a constitutional guarantee. Without it, unions lose leverage to negotiate better wages and safer working conditions for all Canadians,” he stated.

The legal challenges, which may take years to resolve, are unlikely to significantly impact the Teamsters’ dispute but could establish precedents for future labor issues.

Labour Minister Steven MacKinnon referred the matter to the board, citing powers under the country’s labor code. The union claims this infringes on their rights under Canada’s Charter of Rights and Freedoms and that the board acted unreasonably.

Bruce Curran, an employment law expert at the University of Manitoba, noted that the Teamsters’ argument had a reasonable chance of success, highlighting concerns over Ottawa’s overreach in applying the labor code.

The court “may limit the circumstances in which they can use this power in the future,” he suggested in an interview.

The union filed the challenges in the Federal Court of Appeal, requesting an expedited process. However, Canada’s justice system is known for its slow pace, and the losing party is likely to escalate the case to the Supreme Court, prolonging the resolution.

In an emailed statement, CN Rail remarked that arbitration is a neutral process that does not favor either party. CPKC declined to comment.

MacKinnon’s office did not immediately respond for comment, although he previously expressed confidence that his referral to the board would withstand legal scrutiny.

The two companies locked out the workers earlier this month after failed negotiations over a new labor agreement.