Drug use by drivers needs further research

Further research needs to be carried out into the effects of drug use by drivers. Following the legalisation of marijuana for recreational use in some US states, there is concern over the risk this may pose to driving. Most people understand that driving while under the influence of alcohol is a risk. But many people think marijuana to have less of an effect on driving ability and do get behind the wheel following its use. Exactly how many drivers in these US states drive after (or while) taking marijuana is unclear although there is some evidence being collated by police showing a connection between crashes and use of the drug. Nor is it fully understood how much marijuana in the bloodstream will have an appreciable effect on driving ability. A survey by the Insurance Institute for Highways Safety (IIHS) suggests that people who live in states that allow recreational use of the drug are more likely to view it as a highway safety problem than drivers in states without legalised use.