In many countries around the world, people who inject drugs remain at high risk of HIV acquisition not because effective forms of prevention are unknown, nor because they find effective prevention undesirable, but because those in charge, mainly politicians but also bureaucrats, find evidence-based practice politically unacceptable. The evidence for preventive efficacy of harm reduction strategies, most prominently needle and syringe programmes but also treatment programmes such as opiate substitution, is irrefutable.1 However, political responses to drug use issues are varied (...) and complex, so the will to implement appropriate harm reduction programmes in the interests of public health remains lacking in too many jurisdictions. As a consequence, the discussion of how best, in the context of research, to reduce HIV incidence in populations of people who inject drugs but are not offered comprehensive access to known prevention strategies is—tragically—an important one. Dawson et al 2 focus on access to sterile injecting equipment and recognise that this should remain the ‘default’ standard of prevention for HIV prevention trials involving people for whom injecting drug use is the primary risk factor for HIV acquisition. ‘Standard of prevention’ means the background or minimal HIV risk reduction interventions offered to all participants in a trial, regardless of what other investigational interventions they are assigned to receive. The standard of prevention concept is grounded in the ethical principle of beneficence—that researchers and sponsors are obliged to maximise benefits and minimise risks to participants in research studies.3 …. (shrink)