This paper demonstrates tensions between national environmental policies and international free trade rules and traces business reactions to environmentalism through a study of the Can War, a controversy over a Danish ban on beverage cans from 1970 to 2002. At its core was a conflict between Denmark and the European Economic Community (EEC, later the European Union, EU) over free trade versus environmental objectives. This study of the Can War demonstrates how environmental concerns were entangled with national and economic interests, but also how brewers, retailers, and packaging producers used environmental and economic arguments in pragmatic ways and adapted to changing political and economic environments. Thus, the paper adds to the literature on the formative years of environmental politics, with a focus on business interests and a conflict between a nation-state and the EEC in a period when environmental concerns gained political momentum yet remained contested in a system based on free trade. This study also adds to the literature on waste-handling by demonstrating how the Danish return system changed from one based on reuse to one based on recycling; it further shows how beverage cans went from banned to uncontested, everyday objects. Through a comparison with Sweden, the case shows how national businesses influenced the design of new deposit and return systems for single-use packaging, wherein refillable glass bottles became marginalized. Overall, the study offers an understanding of the intricate relationships between environmental policies, business interests, consumer habits, and competing container materials, with aluminum as the winner.