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The interpretation of evidence on the Portuguese decriminalisation of illicit drugs

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Date Commenced:
Project Supporters:

Colonial Foundation Trust

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Project Main Description: 

Ten years post the Portuguese decriminalisation of the use, acquisition and possession of all illicit drugs, a number of diametrically opposed policy conclusions have emerged from evidence-informed analyses of the reform. In an era where evidence is often implied to be the tested, trustworthy tool for generating policies ‘devoid of dogma’ there is a clear need to understand how such competing claims can emerge, and the implications for the pursuit of evidence-based drug policy.

Project Collaborators: External: 

Professor Alex Stevens (University of Kent)


The paper sought to outline the two most divergent accounts on the Portuguese reform, to compare and contrast how they dealt with the three most contested claims surrounding the reform, and to correct misinformation.

Design and Method: 

The accounts of Glenn Greenwald – that the reform was a ‘resounding success’ - and of Dr Manuel Pinto – that the reform was a ‘disastrous failure – were critically analysed to outline their dealing with the impacts of the Portuguese decriminalisation on the prevalence and pattern of illicit drug use, the number of deaths that can be attributed to drug use, and the Portuguese drug situation, relative to the rest of Europe. Accounts were re-contextualised against the available evidence to show how evidence has been used and misused.


Both Greenwald’s and Pinto’s accounts of the decriminalisation showed selective use of evidence (focusing on different indicators, choice of years or datasets) and omission or a lack of acknowledgement of other pieces of the puzzle. Both also showed differential appreciations of data strengths and weaknesses. In so doing, both provided a version of events that offered certitude and support for opposing ‘core beliefs’.

We contend that the promulgation of errors in public discourse can be seen to have both advantages and disadvantages for participants in policy debates. On the one hand, Portugal may not have received the same level of international attention if it were not for such accounts. On the other hand, the misuse of evidence has fuelled clear misconceptions about the reform, shifted debate about how this reform has been spoken of, and potentially constrained opportunities for policy transfer.


The work has been published in Drug and Alcohol Review (2012) (see 'Publications' below for link) and has fed into three presentations by Dr Hughes into the impacts from the Portuguese reform including to the International Drug Policy Reform conference in November 2011.


This analysis corrects some key misconceptions about the impacts of the Portuguese decriminalisation and provides a clear illustration of the danger of presupposing evidence will speak for itself. It also highlights the potential costs for policy advocates of the promulgation of erroneous accounts.

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