Background: For almost a century, the cultivation, sale and use of recreational cannabis has been prohibited by law in most countries. Recently, however, under ballot initiatives four states in the US have legalised commercial, non-medical (recreational) cannabis markets. Several other states will initiate similar ballot measures attached to the 2016 election that will also appoint a new President. As the first state to implement the legislation in 2014, Colorado is an important example to begin investigating early consequences of specific policy choices while other jurisdictions consider their own legislation although the empirical evidence base is only beginning to accrue.
Method: This paper brings together material sourced from peer reviewed academic papers, grey literature publications, reports in mass media and niche media outlets, and government publications to outline the regulatory model and process in Colorado and to describe some of the issues that have emerged in the first 20 months of its operation.
Results: These issues include tension between public health and profit, industry and investment, new methods of consumption, the black market and product testing.
Conclusion: The paper concludes that, while it is too early to determine the impact of the scheme, and noting that it includes some features designed to mitigate adverse impacts, it faces major challenges. Not least of these are the lack of an effective overarching federal regulatory structure, as a consequence of the federal prohibition on cannabis, combined with a rapidly growing cannabis industry which, like other industries, will seek to exploit loopholes to maximise profit.

Highlights:
We examine Colorado's regulatory process of legalised cannabis for adults.
Sourced from peer reviewed academic papers, grey literature, mass and niche media.
Public health, industry investment, methods of consumption and testing are relevant.
The scheme includes features to mitigate adverse impacts but faces major challenges.