Probation officers in the Napo union have voted overwhelming to strike over Tory plans to privatise their service.
Members voted by 84.4 percent to strike on a 46 percent turnout.
Further industrial action is also planned. The union had not set a strike date as Socialist Worker went to press.
Probation officers are challenging Tory justice secretary Chris Grayling’s plans to transfer most of the service to private firms such as Serco and G4S who already run tagging systems.
Private firms and charities are currently bidding for £450 million of contracts—including running treatment programmes and unpaid work.
This will be only the third time that the union has taken action since it was founded in 1912.