Legal limits for driving under the influence of illicit drugs: Large variations between jurisdictions

Abstract

Driving under the influence (DUI) of alcohol or drugs is a major contributing factor to road traffic crashes. Most countries have implemented legal limits for alcohol, and some countries have also implemented legislation on DUI of drugs, in most cases impairment-based or zero- tolerance legislation. Based on searching PubMed, Google Scholar, and the internet, we identified several jurisdictions that had defined legal limits for drugs in the road traffic legislation. This included ten European countries, seven US states, Canada, and New Zealand. Most of these jurisdictions have defined low limits corresponding to the “lower effect limits” proposed by the European DRUID Project, and four countries have also defined higher, graded sanction limits, for some drugs. There were large variations between jurisdictions.