Environmental problems transcend the boundaries of nation states. That fact is a reminder of the physical reality of such problems, but—for good or ill—political and legal imagination is the product of political communities that cluster into nation states. ‘The significance of nation states’ looks at how environmental law is shaped by the legal culture of nation states. It also discusses the difference between civil law systems and common law systems. The internal constitutional arrangements of a country are fundamental to how environmental law develops in a particular legal culture. Is a ‘global environmental law’ emerging?