The Canada Industrial Relations Board has officially declared the ongoing strike by Air Canada flight attendants, organized by the Canadian Union of Public Employees, as illegal. This decision, announced on Monday, came shortly after the union decided to persist with the strike action despite a federal order to return to work.

Air Canada had approached the labor board which then scrutinized the union’s public statements, concluding that the union had disregarded the board's directive to cease the strike. The board highlighted that such non-compliance breached section 91(2) of the Canada Labor Code, compelling the union members to cease their strike by noon on Monday. Despite this, the strike continued, prompting Air Canada to halt its phased plan to resume normal operations.

In response to the stalemate in negotiations, which have been ongoing for eight months, Minister of Jobs and Families Patty Hajdu intervened on Sunday. She directed both Air Canada and the striking flight attendants to engage in binding interest arbitration led by the federal labor board.

The union has strongly opposed governmental intervention. In a statement released Friday, the union argued that intervention disincentivizes fair bargaining on the part of Air Canada. They accused the airline of refusing to negotiate sincerely by ignoring the union’s revised wage proposal and prematurely declaring an impasse.

The legal standing of the strike and the union’s right to strike are underpinned by the Canadian Charter of Rights and Freedoms, which guarantees freedom of association, including the right to strike as per a 2015 Supreme Court ruling. The International Labour Organization's Committee on Freedom of Association also stated that forced arbitration should not replace the right to strike unless the strike pertains to essential services or a severe national crisis.

The union has also highlighted disparities in wage increases over the past 25 years, pointing out that entry-level flight attendants, predominantly women, have seen much lower wage increases compared to their counterparts in other positions such as pilots, who are mostly male.

In contrast, Air Canada on Thursday outlined their offer to the union, which included a 38 percent increase in total compensation over four years, additional health benefits, and pension plans. According to the company, this proposal would significantly enhance the hourly rate for flight attendants compared to other Canadian airlines.

As the conflict continues, the implications of the labor board’s ruling and the ongoing dispute are set to affect not only the parties involved but also the broader public relying on Air Canada's services.