Five police forces could face paying out millions of pounds after a successful age discrimination claim by officers forced to retire after 30 years.
A number of test cases were taken to tribunal on behalf of 250 officers who were pushed out amid 20% budget cuts.
Police Federation members from Nottinghamshire, West Midlands, Devon and Cornwall, North Wales and South Wales Police brought the claims, as well as more senior ex-officers who are in the Police Superintendents' Association of England and Wales (PSAEW).
Hundreds of officers were made to leave their jobs in the wake of the budget cuts, and claimed they were indirectly discriminated against because of their age.
They were compelled to retire under Regulation A19, which was taken to mean that those below chief officer rank could be required to retire after 30 years ''in the general interests of efficiency''.
But today a panel of three employment tribunal judges found that the use of A19 was "not a proportionate means of achieving a legitimate aim".
Mick Taylor from Nottinghamshire Police Federation said: " We are pleased that our decision to support the legal action on behalf of our former colleagues has been vindicated.
"At the same time we are acutely aware that during a period of severe budgetary cuts, any prospective or potential financial burden on the force is no cause for celebration, particularly at a time when many colleagues will be worrying about job security.
"We shall therefore make every effort in assisting the force to the best of our ability, to manage the continuing financial challenges over the coming months and years."
The forces have 42 days to appeal against the decision.
National Secretary of PSAEW Graham Cassidy said: "We obviously are delighted with the decision by the employment tribunal and we note that it was a unanimous decision by all of the judges.
"However this is not a time for triumphalism. There are no winners here. Each of these five test cases represents a police officer at the peak of their service, all of them receiving outstanding annual appraisals for their performance, who were cast aside as a result of what we now know to be an unlawful application of A19."
Dave James and Nigel Rabbitts from the Devon and Cornwall Police Federation said in a statement on the group's website: "It is interesting that the decision is unanimous and well-reasoned.
"It has been a very long and very difficult journey and we are truly grateful to those officers who have assisted in providing witness evidence and to those officers who have helped with funding this.
"Although we have been successful (so far pending any appeal) we are saddened that it had to come to this and that the experience, skills, loyalty and commitment shown by you all, over 30 years of service seemed so easily forgotten."
Chief Constable of Nottinghamshire Police Chris Eyre said the force is "actively considering" an appeal.
He said: " It was necessary for the police authority to consider the use of regulation A19 as a result of the wide ranging austerity measures affecting public services.
"This was a very difficult decision for the Authority and one which was taken after extensive consultation with officers who had 30 years' pensionable service and the relevant staff associations.
"Had there been other viable alternatives the Police Authority would not have made the difficult decision to implement A19.
"We note the decision of the employment tribunal and need some time to consider our position going forward. We are actively considering an appeal and therefore unable to comment further at this time."