An unnerving new short film suggests it's reasonable to be paranoid if you take drugs and drive, as new stricter laws come into force today.
The unsettling advert aims targets people who drive under the influence of drugs, which causes causing hundreds of serious and fatal crashes every year according to the Department of Transport.
Police will use "drugalysers" to test for cannabis and cocaine at the roadside, taking a 'zero tolerance approach' to them and six other illegal drugs.
Under the rules - dubbed 'Lillian's Law' after a 14-year-old killed by a speeding cannabis user - officers can also now take drivers to a police station to test for drugs including ecstasy, LSD, ketamine and heroin. There are now also official limits for eight prescription drugs such as morphine and methadone.
The advert follows a drug driver on a blurry journey home after a night out. He becomes increasingly worried and agitated when he mistakes neon shop signs and lights from windows the blue flashing lights of the police.
He finally arrives home - to find that he was right to be paranoid, as a police car pulls up behind him.
A government survey found 49% of people said that they were a passenger as a car they would not feel comfortable asking if the driver had taken illegal drugs.
Of those who admitted driving under the influence of illegal drugs, 55% said they did so because they felt "safe" doing so. And 60% said they had driven a car when they were unsure if they were still under the influence of illegal drugs.
The ad was created by ad agency AMV BBDO as part of the Department for Transport's road safety campaign, Think!
The laws have been welcomed by the mother of a 14-year-old girl who was the victim of a speeding driver on cannabis.
Lillian Groves died outside her home in New Addington, Surrey, in June 2010, with the driver of the vehicle involved later receiving an eight-month jail sentence.
The tragedy prompted the Groves' family to mount a campaign for stricter drug-driving legislation, with a 22,000-name petition delivered to Downing Street.
Lillian's mother, Natasha Groves, said today: "The new law is very welcome. We are pleased the Government has taken on board the severity of drug driving and acted accordingly by implementing zero-tolerance limits, roadside drug testing and serious penalties for those found guilty.
"The legislation is now up to date and fit for purpose. Having to prove impairment will no longer be a matter of judgment, but a testable fact."
She went on: "When we learnt, in 2011, that this was not already the case, it was incomprehensible. We have fought tirelessly since losing Lillian, and our determination has brought about this significant change. It has been a tough and emotional journey for us all."