The union that represents workers at both of Canada’s largest freight railroads has filed the lawsuits it had promised challenging the orders that forced employees back to work and got the trains moving again, the union announced Friday.

The lawsuits were filed Thursday afternoon, the Teamsters Canada Rail Conference said. But they won’t stop the trains because the government has ordered the union to stay on the job while the arbitration process plays out.

“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,” the union’s president, Paul Boucher, said Friday. “We are confident that the law is on our side, and that workers will have their voices heard.”

One of the railroads, CPKC, declined to comment. A spokesperson for the other railroad, Canadian National, said, “CN would have preferred a negotiated settlement. However, after nine months of attempting to reach a settlement, it was evident that the Teamsters were not looking for a resolution and were happy to keep applying pressure by inflicting damage to the Canadian economy.”

The lockouts stopped traffic in Canada on the crucial railroads this month and halted shipments to and from the United States, cutting off delivery of raw materials, along with shipping of finished products from factories and to retail shelves. They lasted a little over a day at CN and four days at CPKC.

The union doesn’t want to let the precedent stand that the government can block a strike and remove a union’s leverage in negotiations. Prime Minister Justin Trudeau’s government stepped into the contract dispute after both CN and CPKC locked out their workers Aug. 22. Trudeau said he had been reluctant to intervene but saw no other option because of the railroads’ economic importance.

The union challenged the order from Labour Minister Steven MacKinnon that sent the dispute into arbitration and the Canada Industrial Relations Board’s decision Saturday that forced them back to work.

In the four appeals the union filed, the Teamsters asked the Federal Court of Appeal to quash the orders issued for both railroads and declare that the officials didn’t have the power to block a strike. The union’s lawyers demanded “a declaration that the infringement is not a reasonable limit as prescribed by law as can be demonstrably justified in a free and democratic society.”

The union asked the court to expedite a ruling, but it wasn’t clear if that would be approved. Teamsters spokesperson Christopher Monette said he couldn’t predict whether there would be a strike if the union wins because it would depend on the decision’s details and the status of any agreements with the railroads.

A spokesperson for MacKinnon said he wouldn’t comment Friday and would let the legal process play out.

The nearly 10,000 engineers, conductors and dispatchers the Teamsters represent at both railroads couldn’t agree on a new contract despite nearly a year of negotiations. The talks deadlocked over the railroads’ efforts to switch to an hourly based pay and scheduling system instead of the current mileage-based system. The union worried the changes would erode hard-fought protections against fatigue and make jobs less safe.

CN and CPKC have said they offered raises in line with other recent rail industry deals. CN said its engineers make about CA$150,000 a year, while its conductors earn CA$121,000. CPKC said its pay is comparable.

At CN, there was also a dispute over its effort to expand its system of temporarily relocating workers to stem staff shortages. The union didn’t want CN to have the power to disrupt families, but the railroad said the system is voluntary and is already in place in some areas.

CN spokesperson Jonathan Abecassis said arbitration is a neutral process that should help resolve the impasse without favoring one side.

Any kind of prolonged disruption to rail shipments can cause significant problems. Chemical companies had said they might have to slow down or stop production. Water treatment plants worried they could run out of chlorine. Ports and other railroads said shipments would start to pile up if CPKC and CN remained idle.

The two railroads deliver more than CA$1 billion (US$730 million) worth of shipments a day and carry billions of dollars in goods between the U.S. and Canada every month. A number of smaller short-line railroads that handle local deliveries continued operating across Canada but were unable to hand off shipments to either of the major railroads.

CN got moving again the morning of Friday, Aug. 23, after being idle for more than a day, but CPKC did not resume operating its trains until Monday, when the order took effect. The U.S. and Mexican operations of CN and CPKC continued operating, but the stoppage was still a major disruption on both sides of the border.

The railroads have said it might take several weeks to get back up to speed and recover. They both started gradually shutting down more than a week before the lockouts to ensure things like hazardous materials and perishable goods wouldn’t be stranded on the tracks.

A similar rail contract dispute in the United States two years ago — over quality-of-life concerns related to demanding, unpredictable schedules and the lack of paid sick time — ended when Congress and the administration of President Joe Biden stepped in to block a strike at the last minute.

While the Canadian railroads have struggled, U.S. railroads have announced a flurry of new contract agreements with some of their 13 unions four months ahead of expiration. Norfolk Southern announced five more deals Friday to give 55% of its workers new deals, and BNSF also announced agreements with two more unions. CSX started the trend last week and also announced two more agreements Friday. CSX also has more than half of its workforce covered.

All the new U.S. rail contracts would provide average raises of 3.5% a year for five years and improved vacation benefits, but they haven’t yet been voted on by workers.