This paper contains some general reflections on the crime of drug trafficking and a historical overview of its criminalisation in the different penal codes enacted in Spain. It also provides a brief jurisprudential analysis of the aggravating circumstances relating to the crime of public health contemplated in the Spanish legal system, as well as the issues that must be taken into account when determining the jurisdiction of the Spanish courts. An assessment is also made of how organised crime is regulated in Portugal and how the mechanisms for the repression of drug trafficking between Spain and Portugal are articulated through the use of the Treaty between Spain and Portugal for the repression of illicit drug trafficking at sea, signed in Lisbon on 2 March 1998, and how it was used by the Audiencia Nacional in the case of the Eiskos ship.