The right to a healthy environment has been the subject of extensive philosophical debates that revolve around the question: Should rights to clean air, water, and soil be entrenched in law? David Boyd answers this by moving beyond theoretical debates to measure the practical effects of enshrining the right in constitutions. His pioneering analysis of 193 constitutions and the laws and court decisions of more than 100 nations in Europe, Latin America, Asia, and Africa reveals a positive correlation between constitutional protection and stronger environmental laws, smaller ecological footprints, superior environmental performance, and improved quality of life.