The intersections of law enforcement and public health cover a wide range of social and medical issues. Partnerships between police and health agencies are increasingly recognised as critically important, and have a long history in practice, with an evolving history of collaborations. Regardless of whether such collaborations have worked or not, this cross-sectoral approach to complex social issues is often inadequately recognized and understood: law enforcement and public health agencies have traditionally seen their roles separately despite the interdependencies between the two fields. There is now much evidence that such polarisation is erroneous. This introduction outlines the rationale and structure of the first edited collection on La...