Three men from Brighton were arrested in the first week after changes to drug driving rules became law.
Sussex Police said: “Each of the men was stopped and tested using new roadside equipment that indicates whether a motorist has taken cannabis or cocaine, using a swab from inside the driver’s mouth.
“Legislation that came into force on (Monday) 2 March set legal limits for how much of a substance – both illegal drugs and prescription medication – motorists can have in their system while driving.
“Officers no longer need to prove that a motorist is unfit to drive – just that the motorist has an illegal level of drugs in their system while driving.
“A 35-year-old man from Brighton was arrested during a police operation in London Road, Brighton, at 9.35am on Monday 2 March.
“He was later released on bail until (Friday) 24 April while officers wait for the results of the tests.
“A 19-year-old man from Saltdean was arrested at 12.50am on (Saturday) 7 March after he was stopped in Nuthurst Place, Whitehawk. He was released on bail until (Saturday) 25 April.
“A 23-year-old man from Brighton was arrested at Pease Pottage services at 3.45am on (Sunday) 8 March after officers stopped his vehicle because it was being driven erratically.
“He was released on bail until (Tuesday) 5 May.”
The three Brighton men were among arrested by Sussex Police in the first week of the new legislative regime.
Inspector Stewart Goodwin, of the Surrey and Sussex Roads Policing Unit, said: “The fact that we have made eight arrests because of the new legislation and equipment in just a week shows how much of difference the change in the law will make.
“People who take drugs and get behind the wheel can have slower reaction times, struggle to concentrate and can behave more erratically on the roads, putting both themselves and other people in danger.
“We will not tolerate drug driving and would urge anyone who thinks they know someone who is driving after taking drugs to contact us urgently so that we can act.”
People in Sussex can text officers on 65999 with the details of people they suspect of drink or drug driving or visit www.operationcrackdown.co.uk.
They can also contact the independent charity Crimestoppers anonymously on 0800 555111.
To keep up to date with officers looking for drug drivers, follow #opdragonfly on Twitter.
To report someone who is driving while over the limit or after taking drugs, call 999.