The Drug Driving (Specified Limits) (England and Wales) Regulations 2014
Section 5A(1) and (2) of the Road Traffic Act 1988 makes it an offence for a person to drive, attempt to drive, or be in charge of a motor vehicle on a road or other public place with a specified controlled drug in the body, if the proportion of the drug in that person’s blood or urine exceeds the specified limit for that drug. These Regulations specify the controlled drugs for this purpose and the limit for each expressed as a concentration in blood.