Cannabis regulatory system in European Union countries, forensic concept of "doping dose" and medico-legal implications.

Cannabis is the most widely used illicit psychoactive substance in the world. In recent years, in many European Union countries, there has been a decriminalisation of the use and personal possession of cannabis for recreational purposes. There has been a spread of medical cannabis, as well as marketing of cannabis products at low concentrations of delta-9-tetrahydrocannabinol (Delta-9-THC), the major chemical to which cannabis owes its psychotropic effect. The percentage limit of this substance, only recently set by the European Court of Justice, must be distinguished from the "doping dose" of Delta-9-THC, namely, the dose which causes psychotropic effect in the consumer. Our study analyses and summarises the regulations in the countries of the European Union on the penalisation of recreational cannabis, the legalisation of medical cannabis and limits on percentage of THC imposed locally. Based on the analysis of a recent judgment of the Italian Supreme Court of Cassation, we discuss the importance of the role of the forensic toxicologist in the scientific definition of "doping dose". The distinction between the doping dose of THC and the percentage of THC contained in the marketed cannabis product is vital when establishing fair punishment in the event of a crime.