Sustainability is beginning to transform the food industry with environmental, economic and social factors being evaluated and implemented throughout the supply chain. This chapter builds an analysis of the EU and US food systems and compares their respective regulation of sustainability as it relates to "green" or environmentally-friendly processing. The history and development, organization and general food law provisions of the respective EU and US food regulatory systems reveal differences in cultural history, institutional organization, and legal philosophy, which helps explain the various sustainable food production approaches taken by the US and the EU. The EU and the US have been involved in international actions toward sustainability, and have enacted national policies to implement the commitments. The EU has enacted more mandatory measures than the US in terms of environmental practices, mostly due to its application of the precautionary principles; yet, both encourage sectors to implement environmental management systems. Subsidies are increasingly conditioned on producers' use of environment-friendly practices, and national organic programs largely influence the US and the EU's sustainable agriculture policies. In addition to government regulations, sustainability in the food sector is promoted through private standards amongst processors, producers and retailers. These private standards have international trade implications and present several legal challenges that range from threats to the viability of the food regulatory system to practical concerns relating to capacity, contract compliance and the risks of careless standard-setting. The biggest challenge remains to balance practices that are environment-conscious while remaining profitable and beneficial for all parties involved.