The United States and the majority of the other wealthy nations whose institutions dominate the world banking industry have enlisted their banks in the crusade to eradicate the perceived international menace of drug abuse and drug trafficking. Although the industrial nations share a general commitment and even some specific policies to counter drug trafficking and abuse, the ways in which they have regulated their banking systems to that end vary greatly. So also do the costs and levels of success. Using banks to stop drugs focuses on the central dilemma of the large-scale drug trafficker: how to pour large amounts of illicit profits into the legal economy. The large-scale drug trafficker must launder the large cash flows that the drug enterprise generates. Banks are the weak link in money laundering. Both Switzerland and the United States have acted on this and fashioned special resolutions to monitor the acceptance of deposits by banks, and thus, in theory, bar the entry of illicit profits into the financial system. The principal difference between the Swiss and the American systems is the balance struck between broad self-regulation and narrow state regulation. This balance largely determines the efficacy and cost of both systems and reflects both cultural differences and legislative choices. The American regime, with its surfeit of formalistic requirements, has proven costly to banks, yet has been only marginally effective at stopping money laundering. The Swiss regime, in contrast, emphasizes subjective, organic analysis, and leaves important regulatory oversight functions to an organization created by private inter-bank contract. This essay concludes that the United States ought to move toward a system based on self-regulation like that of Switzerland. 194 footnotes