Random drug tests for police
Staffordshire Police are introducing the tests on any officer allowed to drive patrol cars with their blue flashing lights on.
Forty-nine officers have already been tested and provided negative results in the crackdown.
Now an average of 20 officers a month are to be tested at random times.
Superintendent Stephan Popadynec who heads the force's professional standards unit, said: "This does not imply any lack of trust in the professionalism of our staff.
"Such tests minimise the opportunity for people who misuse substances to enter the police service.
"They also help to monitor the health of the organisation and ensure the health and safety of our staff, particularly those in vulnerable and safety-critical posts."
National legislation allowing drug testing of officers was adopted by the force three years ago and had been limited to firearms experts and driving instructors.
Police chiefs plan to extend the drug testing to police staff by the end of the year.
Staffordshire Police Federation chairman Mark Judson said the first batch of drug-tested officers had been concerned about the practice.
He said: "If we do these unannounced tests and nobody is failing a single one then it may not be necessary to carry on doing as many.
"If it identifies a problem there is a possible need to extend it.
"But after doing 20 people a month for three or six months then it may be that we don't need to do it at this level."
Any officer who tests positive could end up with a criminal conviction, a misconduct hearing and eventual dismissal. But the federation hopes the force will take into account an individual officer's circumstances and the type of drug if a bobby is not prosecuted.
Mr Judson added: "If it wasn't a serious classification problem the force might deal with that in a more sensitive and considered way."
Cheshire Police have no plans to bring in the drug tests.
Ken Davies is discipline liaison officer at Cheshire Police Federation.
He said: "There is a national policy on drugs and alcohol, but each force can adapt its own policy along those guidelines."
Read more:
Latest police news and appeals
Caught on camera - can you help
Operation Nemesis: the fight against drugs
Comment on this story