Why do countries have different policies on e-cigarettes?

This paper is based on research into the history of policy making and institutions in 3 countries which have taken different approaches to the regulation of e-cigarettes. In the UK the tradition of harm reduction through nicotine has helped form a response which has endorsed e-cigarettes .The US has a cessation only anti tobacco agenda while Australia has effectively banned e-cigarettes. Each country filters its policy making through different histories, regulatory apparatuses, policy players and prioritises the health of different groups within the population. This long-standing context  helps explain differing policy responses.