Ryan Remiorz/The Canadian Press Striking Canada Post workers walk the picket line in front of the Saint-Laurent sorting facility in Montreal on Nov. 15, 2018.

The Canada Post strike saga entered a dramatic new chapter last week when the federal government announced it was considering using a law to get postal workers back on the job. UPDATE: The Senate passed Bill C-89 on Monday evening. It goes into effect on Tuesday at noon. Last week, Labour Minister Patty Hajdu said the Liberal government did not want to resort to using back-to-work legislation, but noted there was "limited progress" in the talks between the Canadian Union of Postal Workers (CUPW) and Canada Post and that the feds had "exhausted" all options. Hajdu said the Liberals maintain that the best outcome is one that is reached by both parties at the negotiating table, but if that can't happen, then the government would have to intervene.

Two days later, the government tabled the Postal Services Resumption and Continuation Act, or Bill C-89. Back up. What is back-to-work legislation? In some ways, it's just that: a law that aims to get employees back on the job. But it's more complicated — and controversial. "The basic premise of labour law and collective bargaining in Canada is that the parties are allowed to engage in their own collective bargaining and then to engage in strikes and lockouts as a way of applying leverage if they can't get agreements through the bargaining process," said Michael Mac Neil, an associate professor at Carleton University's law department, told HuffPost Canada. It's used as a "last chance measure" when two parties can't reach a deal on their own, he added. The government says it's wading into the Canada Post issue because both parties have not made any progress in negotiations and that it has "exhausted" all options. You're telling me a government can force me to work? This is my nightmare. It's time for revolution. No, it's not that broad. A federal or provincial government can mandate some employees back to work if the type of job they have is deemed essential to issues like health and security, Mac Neil said. Of course, the jobs have to be in the government's jurisdiction, too. Canada Post is a Crown corporation, so it's a federally-run shop. Similarly, the months-long strike at Toronto's York University, which fell under the provincial government's jurisdiction, was also ended with back-to-work legislation from the Ontario government. "When the government makes an assessment that the amount of harm that's being caused by a strike is more than the general public should be required to bear, then they will on a one-off basis pass legislation ordering the strike to stop and ordering the workers to go back to work," he said. This also involves installing some type of dispute-resolution system for the two parties, whether it's mediation or arbitration, or both. So the back-to-work law's main goal is to end a strike, then? Yes, but another complicating factor is that the Supreme Court ruled in 2015 that the right to strike is protected by the Constitution. "So for the government to demonstrate intervening and putting a limit on strikes, it has to have a very persuasive case for doing so," Mac Neil explained, "which usually means it has to be in a position to demonstrate that there is some considerable harm being done by the strike or the lockout."

Fred Chartrand/The Canadian Press Members of the Canadian Union of Postal Workers occupy Minister of Environment Catherine McKenna's community office in Ottawa on Nov. 23, 2018.

What is the harm being done in the postal strike, then? Great question, made-up voice I've randomly introduced to ask me things. The government is arguing that the harm here is financial. Hajdu said the postal system is an "essential service," and that small businesses that rely on it to deliver their goods over the busy Christmas season could go bankrupt if the situation isn't remedied quickly. "And that's one of the controversial issues in relation to the use of back-to-work legislation," Mac Neil noted. "Should it only be considered for situations where there is sort of a jeopardizing health and safety of the public? Or should it also be able [in situations] where it's causing just economic harms?" How does the law actually get people back on the job? In this case, Bill C-89 would give a mediator-arbitrator chosen by the government 90 days to try and reach contract settlements with the union and Canada Post. If that doesn't work, the arbitrator could choose a settlement for the two parties or green light one of the final proposals that either party has suggested. Once it receives royal assent, the law effectively makes striking — for the affected employees, specifically — illegal, Mac Neil said. What actually deters people from striking, however, depends on several factors. The employer could choose to file an injunction against people who don't show up to work. If they don't comply, he said, they could be charged with contempt of court. That could lead to fines and even imprisonment, "especially if union leaders are the ones continuing to call for a strike."

The Canadian Press Idle Canada Post trucks sit in the parking lot of the Saint-Laurent sorting facility in Montreal as rotating strikes hit the area on Nov. 15, 2018.

The law could also have monetary fines baked into it for any employees (or employers) who break the rules. Bill C-89, for example, could impose fines of between $1,000 and $50,000 per day on anyone found in contravention of the Act, and up to $100,000 per day against Canada Post or the union if they are found guilty of violating its terms. And there's always the possibility of "disciplinary action," Mac Neil said. "They could suspend them or fire them." More from HuffPost Canada: Feds Defend Back-To-Work Law For Canada Post Workers As Constitutional

Canada Post Strike To End As Senate Passes Back-To-Work Legislation I'm going to go out on a limb here and guess the postal workers' union is not happy about this. Not one bit. CUPW, which is calling for better pay, more job security and minimum guaranteed hours for its workers, among other things, said in a statement over the weekend that a back-to-work law would send its workers "back to the same old unresolved problem." "Postal workers will not accept another violation of our right to free collective bargaining," said Mike Palecek, CUPW's national president, in a statement. "It's not just a matter of our Charter rights. This bill legislates continued injuries, unpaid work, gender inequality, and general dishonesty and disrespect." The union says "all options are on the table" when it comes to pushing back should the legislation pass. One of those options is taking the government to court, according to Meghan Whitfield, president of CUPW's Toronto Local 626. In 2011, the union launched a similar challenge to the former Conservative government under Stephen Harper. It ended with a victory for postal workers after an Ontario court ruled the Tories violated the workers' constitutional rights by ordering them back to work.

The Canadian Press A Canada Post employee drives a mail truck through downtown Halifax on July 6, 2016.