If passed, the bill would appoint a mediator-arbitrator to help Canada Post and the union representing its workers come to an agreement.
Workers are legislated back to work in 1987, 1991, and again in 1997. "We wouldn't come down this road, however, we have exhausted every option".
Canadian Union of Postal Workers vows to fight in court if the bill is passed.
As the parliamentary scene unfolded on the Hill, out on the lawn Canada Post employees had gathered with signs, even a large crafted head of Prime Minister Justin Trudeau.
Rotating strikes have been underway since early October and the job action is already affecting pre-Christmas deliveries right across the country.
Canada Post delivers two-thirds of the nation's online shopping and the last six weeks of the year are its busiest due to the holiday rush.More news: Black Friday 2018: The 7 best gaming deals
More news: Killed, 47 Injured in France Gas Protests
More news: FCC Grants SpaceX Permission to Deploy 11,943 Broadband Satellites
NDP Leader Jagmeet Singh accused the Liberals of hypocrisy, professing to believe in the right to collective bargaining while bringing in what he called the "worst, most draconian" back-to-work legislation.
New Democrat MPs had voted against a motion to speed up debate on the back-to-work legislation, with many making an elaborate show of walking out of the Commons after voting, raising their fists in salute to postal workers watching from the public gallery.
Canadian Union Postal Workers wins challenge of previous back-to-work legislation in the Ontario Supreme Court.
The Liberal government did not come to the decision lightly, Hajdu told the Commons after tabling the bill, along with a concurrent motion to fast-track the legislation if necessary.
Members of the Canadian Union of Postal Workers have held rotating walkouts for a month, causing massive backlogs of unsorted mail and packages at postal depots. "Toronto local reports that rather than the "hundreds of trailers" that Canada Post reported, they have about seventy - a backlog that can probably be cleared in a few days".