This Article focuses on lessons learned from state practice in environmental justice (EJ) mapping and screening, and their relationship to the central issue of cumulative impacts—the reality that EJ communities typically suffer from a concentration of pollution sources and negative land uses as well as health and social vulnerabilities. These lessons are based on work in California and the development, use, and impact of the California Environmental Protection Agency’s CalEnviroScreen tool; the Article also examines the U.S.

The principles of “common but differentiated responsibility” (CBDR) and sustainable development play an integral role in international environmental law. However, these principles have come under fire in recent years, particularly from the global North, which has grown impatient over the lack of contribution on climate change from the emerging economies. Much effort has been expended toward the establishment of greater contribution, and the shouldering of greater responsibility from these countries.