The Public Service Alliance of Canada won a final victory Thursday in a pay-equity case against Canada Post that goes back a generation.
The Supreme Court of Canada, in a rare ruling from the bench delivered by Chief Justice Beverley McLachlin, sided with the union in the $150-million dispute.
The unanimous court said reasons will be delivered later.
The union welcomed the decision, but decried the amount of time it took to settle the case.
"Today we celebrate a hard-won victory for equality," said Patty Ducharme, the union's national executive vice-president. "But the fact that this took 28 years is completely unacceptable.
"Canada needs a proactive pay-equity law that ensures that women won't have to wait decades to be compensated for the value of their work."
The union said in a news release it will push Canada Post to issue back-pay cheques quickly.
"Anyone who worked as a CR at Canada Post between 1982 and 2002 will now be eligible to receive pay-equity payments."
Ginette Chartrand, one of the women who filed the original case against in 1983, said she wept when she heard of the decision.
"We believed in our case," she said. "But we did not expect a decision so quickly. I cried," Ms. Chartrand said in a union news release.
PSAC claimed in August 1983 that women were being discriminated against under the Canadian Human Rights Act because they made less than men in comparable Canada Post jobs.
The Canadian Human Rights Tribunal compared wages between 6,000 current and former mainly female clerical staff and the predominantly male postal operations group.
The complex case relied on more than a decade of human rights hearings — some 410 working days between 1992 and 2003 — and featured complicated number-crunching that attempted to compare the work done by men and women.
The tribunal ruled in 2005 that Canada Post had violated the act and awarded back pay and interest of about $150 million.
But the Federal Court of Appeal set aside the tribunal's decision, saying the finding of discrimination simply could not be supported.
"In our respectful view, the tribunal became confused, and therefore fell into error," Justices Edgar Sexton and Michael Ryer wrote for the majority on the appeal court.
In the late 1990s, the federal government settled a pay equity dispute with 230,000 current and retired employees to the tune of $3.2 billion.
The Conservatives sought to bring an end to the lengthy and costly court battles over pay equity when they passed a controversial measure in 2009 requiring workers to secure pay equity during collective bargaining rather than in courts and tribunals.