In their commentary, Caulkins et al. 1 reflect on Nutt and colleagues' recent efforts to develop evidence-based scales to assess the harms of drugs, or to rank drugs on the basis of their harmfulness 2, 3. Caulkins et al. vigorously criticize these efforts as ‘fundamentally flawed both conceptually and methodologically’ as well as ‘misguided in principle and particulars’. We share some aspects of the methodological and conceptual criticisms offered by Caulkins et al. vis-à-vis Nutt et al.'s proposed harm scales. We agree, for example, that it is difficult, and can be empirically counterproductive, to try to reduce the harms of drugs into a single indicator measure. The harms and risks related to drugs are clearly multi-dimensional and occur on a variety of levels, and as such would be better expressed by a harm matrix, as has been suggested by others 4, 5. We ourselves, in an attempt to operationalize definitions of ‘harm’ as a conceptual foundation for empirically measuring ‘harm reduction’, proposed such a multi-dimensional matrix more than a decade ago 6. This proposal emphasized the need for measurements of harm at both individual and social levels, also on different axes differentiating acute and long-term harms. We also emphasize—or reiterate—that it is difficult, if not impossible, to assess, quantify or compare any drug's harm independently of its social context. In other words, the currently perceived, assessed or actual harms of alcohol, tobacco or heroin, as examples, are both influenced and constrained by the (desired and undesired) effects that current regulatory or market systems of control have on them 7. That is, as Caulkins notes, harms (or benefits) are highly dependent upon social milieu. However, having acknowledged these potential limitations in Nutt et al.'s models and the methodological weaknesses, and while agreeing on the need for further scientific debate to refine and advance the science of assessing harms as part of the evidentiary base for policy formulation, we submit that these reservations and concerns are of limited relevance when compared to the current lack of any scientific base for present drug control policy. Our opinion is that these methodological concerns definitely ought not to constitute the grounds for categorical dismissal or rejection as advocated by Caulkins et al. Using our own country, Canada, as an example, it is readily apparent that drug scheduling within the Controlled Drugs and Substances Act (CDSA) 8, 9 or provincial and territorial regulatory control systems have little to no footing in scientific evidence; neither do they follow elementary principles informed by empirical logic. If we assume that public health and welfare should be guiding principles for good and desirable psychoactive substance control policy we would, for example, not expect to see the third most commonly used drug (cannabis) to be scheduled and regulated alongside drugs such as heroin and cocaine, while alcohol and tobacco are not only legally available but are openly traded in Canadian society and cause thousands of cases of deaths and injuries each year 7. In comparison, cannabis consumption has zero directly attributable mortality and relatively little major associated morbidity in the majority of users 10, 11. Historically, drug scheduling in Canada originated as a tool of socio-economic control of non-white minority groups, and hence the original drugs included successively in the drug control schedule were opium, cocaine and cannabis (1908–1925) 12, 13. The conceptual framework laid then, and which persists today, had neither public health, nor pharmacology, nor any attempt of rigorous harm quantification as a foundation. Interestingly, tobacco prohibition was considered briefly in Canada during this period, but not considered feasible given its popularity among the dominant white and Anglo-Saxon middle class 14, 15. Alcohol prohibition was approved in Canada by referendum in the late 19th century, yet was never enacted by the federal government (due mainly to resistance from Quebec), and was later imposed on supply largely as a consequence of World War I 16. Thus from a view of current public health and policy perspectives, applying Nutt's harm scales, flawed and limited as they may be, would constitute a quantum leap of progress towards evidence-based and more rational drug policy in Canada and elsewhere. In applying Nutt's harm scales, drug scheduling and control would, to a substantial extent, be informed by scientific evidence of risk and harms from drugs, rather than rooted in the anachronistic skeletons of socio-economic class and control, which arguably may do as much (or more) harm to public health in Canada as the drugs it is supposed to control 17-19. The benefits from grounding Canadian drug control policy in Nutt et al.'s harm scales could be expected to be tangible until at least after their critics have revised and improved them. None.