The article responds to the legal situation following the publication of a decision of the Constitutional Court (File Ref. Pl. ÚS 13/12, dated 23rd July 2013) to the effect that it is unconstitutional for a "quantity greater than small" of illicit drugs (referred to as "narcotic and psychotropic substances" in the Czech laws) to be determined by a government regulation (bylaw).
The authors assume that because of the absence of a general definition of illicit drugs, including a definition of the principal characteristics of this category of substances, in the Czech legislation a similar judgement of the Constitutional Court may be expected sooner or later with regard to the legal determination of "what illicit drugs are" in terms of the criminal law. The authors attempt to summarise the effective international and supranational legislation and practice in selected developed countries while proposing a legislative definition of what should be considered illicit drugs for further expert and public debate.