About 400 police officers who were forced to retire have lost their claim for age discrimination at a tribunal.
Many of those at forces across the country with more than 30 years service were forced to step down under the "A19" regulations.
The employment appeals tribunal upheld an earlier appeal by police forces.
Officers in Nottinghamshire, West Midlands, Devon and Cornwall, North Wales and South Wales could now take the case to the High Court.
Nigel Rabbitts, of the Devon and Cornwall Federation, said it was a "blow" to those involved.
The officers had won an earlier judgement, prompting fears that police forces across England and Wales could be forced to pay millions of pounds in compensation.
Invoking the A19 rule saved the forces more than £66m in wages, the BBC found last year.