Environmental law in the United States is a body of legislation, traditional principles, agency regulations, and contract and treaty obligations governing business, government, and private activities affecting public health and the natural environment.

We have seen an explosion of environmental law since Earth Day 1970. This public celebration was the spark of the environmental movement in the United States, calling for major reforms to bring about clean air and water.

Since then, environmental law has come of age. It has taken the form of comprehensive statutes on a range of problems in response to scientific knowledge and public concern. It has grown from just federal and state statutes to include local land use bylaws and ordinances. It has gone beyond just government regulation controlling pollution to encourage beneficial activities by tax incentives and financial grants. It has changed how government works by imposing serious limits on management of our forests, minerals, navigable waters and other public resources and by requiring environmental impact statements for government projects and permits. it has drastically altered how industry, government, and landowners make decisions.

The courts have been willing to enforce the letter and the spirit of environmental law. Some of our most important advances of environmental protection have been by virtue of court decisions.

The courts have ruled that all government agencies (even the military) are responsible for the environmental impacts of their activities. They ruled that citizens can sue to enforce environmental law against polluters and against the government itself. They ruled that tough penalties imposed on violators are appropriate. They ruled that some serious violators must cease operations and pay money damages to victims of pollution.