Distinguishing between drug possession for personal use and supply and trafficking is widely acknowledged as one of the most difficult and controversial issues facing drug legislators and policy makers. To address the problem, two solutions are typically enacted: the threshold scheme and the "flexible" model.
Threshold quantities (TQs) for drug law and policy are being experimented with across many jurisdictions. States seem attracted to their apparent simplicity and use them to determine, for example, whether: a possession or supply offence is made out (e.g. Greece); a matter should be diverted away from the criminal justice system (e.g. Portugal); or a case should fall within a certain sentencing range (e.g. UK).
A wider trend for drug law reform is arising out of a felt need to make legislation more effective and more humane. Within this trend, a number of countries have considered decriminalisation or depenalisation models and many have, at least initially, considered threshold quantities as a good way to distinguish between what is possession and what is supply or trafficking and as a means to ensure that the sentences imposed are proportionate to the harmfulness of the offence.