The regulation of drugs presents a challenge for liberalism: how can punishing a person for an action that harms only himself or herself be justified? For public policy a related difficulty is to justify the differential treatment of drugs and alcohol. Philosophical arguments suggest that current regulations are unjustified, and that some currently illegal drugs should be treated no more harshly than alcohol. However, such arguments make little or no impact in public policy discussions. This generates a further problem: to understand the different perspectives of philosophical reasoning and public policy so that philosophical arguments can have a greater role in public policy debates.