Roadside drug testing kits were last week approved for use by the UK police force to test drivers who they suspect may be under the influence of drugs while driving. The use of roadside saliva drug testing kits, will make it much easier for the police to decide if a driver is under the influence of drugs.
Previously if the police stopped a driver and suspected they were impaired by drugs they would do a field impairment test which are a series of tests to assess a drivers capability to drive. If the police felt the driver was impaired they would then take them back to a police station and they would perform a blood drug test. Drugs can impair driving in many ways similar to alcohol and the penalties are the same as for drink driving. Some drugs may increase anxiety and aggressive behaviour, and lower concentration which can also impair driving.
The law is about to change in March 2015 when a new UK law will come into force which will make it easier for the police to test and to prosecute drivers who are under the influence of drugs. Drugs that will be covered under the new law include Cannabis, Cocaine, Ecstasy and Ketamine. The drug driving limits will be very low.
Here is a link to a pdf with some info about drug driving limits http://www.legislation.gov.uk/uksi/2014/2868/pdfs/uksi_20142868_en.pdf
Some of the drugs including on the list are prescription drugs.