Despite claims to the contrary, decriminalization appears to have had a positive effect on crime. With its recategorisation of low-level drug possession as an administrative rather than criminal offence, decriminalisation inevitably produced a reduction in the number of people arrested and sent to criminal court for drug offences – from over 14,000 in the year 2000, to around 5,500-6,000 per year once the policy had come into effect. The proportion of drug-related offenders (defined as those who committed offences under the influence of drugs and/or to fund drug consumption) in the Portuguese prison population also declined, from 44% in 1999, to just under 21% in 2012.
Additionally, decriminalisation does not appear to have caused an increase in crimes typically associated with drugs. While opportunistic thefts and robberies had gone up when measured in 2004, it has been suggested that this may have been because police were able to use the time saved by no longer arresting drug users to tackle (and record) other low-level crimes. Although difficult to test, this theory is perhaps supported by the fact that, during the same period, there was a reduction in recorded cases of other, more complex crimes typically committed by people who are dependent on drugs, such as thefts from homes and businesses.