More drug-drivers are being arrested and convicted since new laws were introduced in England and Wales last year, the government has said.
The Department for Transport cited figures from Cheshire Police that showed arrests there were up 800% to 530 from 70 in the previous year.
Legislation was brought in covering legal driving limits for 17 illegal and prescription drugs in March 2015.
Previously, police had to show driving was impaired by drugs to prosecute.
Police forces have been given an extra £1m to train officers, purchase drug screening equipment and pay for samples to be analysed as a result of the new law. Under the new legislation, officers can use roadside swab tests to check for cannabis and cocaine. Further tests can be carried out for other drugs covered by the law at a police station.
People are not penalised if they use prescription drugs such as morphine and methadone within recommended amounts.
The Department for Transport said 1,888 drug screening tests were carried out in England and Wales over the 2015 Christmas period, with nearly half producing a positive result.
Road safety minister Andrew Jones said:
“Thanks to our tougher law, police are catching and convicting more dangerous drivers. The government will continue to stand shoulder-to-shoulder with police as they work tirelessly to protect the public while recognising enforcement alone is not the answer.”
Cheshire Chief Constable Simon Byrne said his officers had taken a “no nonsense approach to target criminals who use our road networks”.
An AA survey of more than 26,000 motorists found that 88% supported the clampdown against drug-drivers.
Edmund King, president of the motoring organisation, said: “Drug-driving is often the hidden killer on UK roads. We need to make it as anti-social as drink-driving. The new law and greater enforcement will help achieve this.”
Neil Greig, of the Institute of Advanced Motorists, said the new law was “one of the most successful road safety measures in the last 10 years”.
The law does not apply to Scotland and Northern Ireland but motorists can still be arrested if they are unfit to drive because of drugs.