Going specifically into the European case, following the European Monitoring Centre for Drugs and Drug Addiction , this distinction was further refined to perform the analysis: decriminalisation through reforms that remove the prison sentences for minor offences ; depenalisation, where the offence is still criminal, but a reduction of the maximum prison sentence is operated ; depenalisation where the offence is still criminal but the likelihood of sanctions being applied is reduced by facilitating the closure of minor cases ; increase of the penalties, where the possession for personal use is a civil offence but the reform increases the penalties attached to it ; increase of the penalties, where the possession for personal use is a criminal offence and the reform increases the penalties attached to it . To better understand how the European countries included in our study have been categorised and understand each specific policy change, Table 2 provides an overview of the broad category into which the policy changes fall, the specific type of reform and a description of the situation pre- and post-reform in each country.

Seven countries that did not pass any cannabis law in the observed period were used in the analysis as a control group: France, Iceland, Latvia, Malta, the Netherlands, Norway, Sweden. Four additional countries that reformed their cannabis control policies in the observed period were excluded from the analysis because the related ESPAD data were not available for all the considered years: the United Kingdom , Estonia , Luxembourg and Belgium .This paper assessed whether the cannabis policy changes occurred in 13 European countries in the period 2001–2014 were associated with significant outcomes among adolescent students. In particular, to inform discussions about the evaluation of policy developments related to cannabis that might increase the availability of this substance within Europe, we analysed changes in the perceived availability of cannabis. In order to check the possible association with changes in the prevalence of use of this substance among adolescent students, we differentiated between different patterns of use . This has been done in order to account for the fact thatusers are not equal, and that there is a group that, although restricted, is more at risk of developing cannabis-related problems, i.e. frequent users .

This study contributes to clarify the scarce and inconstant literature on European states , providing important information about policy outcomes and efficacy. Moreover, differently from previous studies that simply categorised cannabis control policies into a dichotomous measure , this study takes account of the fact that there is a great diversity of forms that relaxation or increase of prohibition can take in practice , by refining the investigation following the analysis proposed by EMCDDA . In fact, ignoring the significant heterogeneity in these policies, has been highlighted to contribute to what appear to be mixed results from evaluations . In order to better interpret the results, for each country a description of the situation pre- and post-reform has been provided. By combining data from five waves of the ESPAD survey, our data include a timespan of more than 15 years, covering the period before and after the implementation of each of the national drug policy reforms. Results are based on a DiD model. Regarding the availability of cannabis, we find that none of the decriminalisation and depenalisation reforms seem to be linked to an increase in the perception of easy access to this substance by the general population of students, nor it is so among non-frequent and frequent users.

This finding suggests that the common assumption that cannabis availability will increase with the relaxation of prohibition might not apply to the European cases. This means that in a country like Portugal, where the personal possession of cannabis was decriminalised in 2001, the perceived availability of cannabis did not increase as a result of the reform compared to a country like France, where the possibility of incarceration for the possession of cannabis for personal use is still foreseen. Among the policy reforms increasing the penalties for cannabis personal possession, those increasing the administrative penalties attached to this offence are actually associated to a decrease in the rate of students perceiving cannabis as easy to obtain. This result might be a good indication as it has been demonstrated that those who believe they have easy access to cannabis have also a greater risk for uptake, higher consumption frequency, as well as the progression to regular use and abuse . However, the fact that among users this association persists only for the non-frequent ones, suggests that the channels of access to the substance by frequent users, such as domestic production and supply networks , might not have undergone significant modifications.