The chairman of the Police Federation in North Yorkshire has said it may take legal action over plans to retire officers forcibly.
On Monday the county's police authority agreed to back regulation A19, which gives the chief constable the power to implement redundancies.
The measure allows North Yorkshire Police to force officers with more than 30 years' service to retire.
But federation spokesman Mark Botham said legal action was a possibility.
It comes as the force seeks to cut 210 jobs over the next four years.
North Yorkshire Police Federation has questioned the effect the move would have on the force's sustainability.
Spokesman Mark Botham said the federation feared a "massive effect".
"Since 2007 we have already lost 150 police officers," he added.
"To lose another 210 will bring us to a level lower than at any time since North Yorkshire Police has been in existence."
And he added: "We are extremely disappointed that they haven't waited for the result of government cutbacks or the police pension review.
"This is what our national federation has been warning about and no-one has been listening.
"And it's on that basis that I've said we reserve the right to take legal advice and legal action."
A North Yorkshire Police Authority spokeswoman said on Monday the measure gave the chief constable the power to force long-serving officers to retire, should the number of required job cuts not be met through voluntary redundancies.
The force's chief constable, Grahame Maxwell, said employing fewer people would inevitably have an impact.