The union representing Canada Post employees will mount a legal challenge against legislation forcing them back to work.
The back-to-work bill was adopted last weekend following a 58-hour filibuster by the NDP.
Alain Duguay, head of CUPW's Montreal local, told The Canadian Press the union will seek legal recourse in an effort to overturn the legislation.
He said the decision was made by the union's national executive after a long meeting on Tuesday in Ottawa.
Mr. Duguay said details about the effort - such as whether the law will be challenged entirely or in sections - have yet to be determined.
In the meantime, said Mr. Duguay, postal workers do not plan to defy the law, meaning mail delivery will continue while the law is being contested.
The union is also considering lodging a complaint with the Human Rights Commission, claiming discrimination against newer employees who will not have the same pension benefits as older ones.
The back-to-work legislation forces postal workers to accept wages that are less than Canada Post's last offer.
On non-wage issues, it imposes a form of winner-take-all arbitration in which CUPW and the corporation will each make a final offer, one of which will be accepted.
Salary issues are not included in the arbitration process.
The union says it still hopes a new collective bargaining agreement can be struck before the arbitrator makes a decision.
Postal workers began a series of rotating strikes on June 3 and Canada Post brought delivery to a complete halt by locking out employees on June 14.