Drivers under the influence of drugs or alcohol will be targeted during a summer crackdown in England and Wales.
Drug and drink drivers could end up in prison
Police say drug-driving is a "growing problem" and can be as dangerous as driving after too much alcohol.
People suspected of being "unfit to drive" through the use of illegal or prescription drugs or alcohol will be asked by police to take roadside tests.
The field impairment test includes eye pupils' examination, standing on one leg and walking in a straight line.
Drivers who refuse to take the test can be arrested.
Chief Constable Steve Green, of Nottinghamshire Police, said people needed to be responsible in their attitude to driving.
"The police service is not willing to tolerate this type of offending and it is our intention to crack down heavily during this campaign," he said.
He said the field impairment test included four psycho-physical tests which indicated whether a person's driving ability was impaired.
"If it is deemed to be the case and they are found guilty of such an offence, then the courts can impose the same penalties as for drink-driving," he added.
Chief Superintendent David Snelling, of London's Metropolitan Police, said drink and drug driving impaired the ability to judge speed and distances, reduced concentration and slowed reactions.
"The chances of being involved in a collision are significantly increased - which may result in serious injury or death," he said.
"As well as these dangers, you may lose your job as a result or end up in prison.
"The safest option is not to drink at all if you plan to drive."
Steve Green, of the Association of Chief Police Officers, says legally available prescription drugs should be included in the ban.
"We've got to err on the safe side. If a drug can have that result [of impairing driving ability] then I think we've got to say to people I'm sorry, if you need this drug, then you shouldn't drive."
The month-long campaign runs until 2 September.