The claim against Glasgow City Council by around 8000 workers was part of what has been called the second wave of equal pay and sought to challenge how the authority compared the salaries of female staff with males performing comparative roles.
Had the claim been successful the bill to the council would have ran into many millions of pounds, with speculation from within the authority that wages would have been cut as a result.
It followed a landmark legal ruling last year which opened the door to thousands of new claimants by allowing claims to be made within six years, where previously they had been time-barred after six months.
One of the three legal firms said it is "giving serious thought to" demanding a reconsideration of the 190-page judgement, which followed a 38-day hearing.
The legal teams for both unions and individuals have until late January to lodge an appeal and 20 days for the reconsideration.
The claim dates back to 2006 after Glasgow settled its equal pay dispute at a cost of around £50 million and went about re-evaluating all its jobs and creating a new pay scale.
But unions and solicitors argued the new system inherently discriminated against female workers.
A Fox and Partners spokeswoman said: "Regrettably the panel have found against the claimants. We will be meeting with our legal team in the New Year to consider our next course of action."
A city council spokesman said: "We are committed to ensuring all our employees are paid the appropriate rate for their job."