NEPA was a set of policies intended to protect the environment from humans, and required statements on the environmental impact of construction projects in order to better carry out its purpose.

The Federal Land Policy and Management Act of 1976 ensured that land under the Bureau of Land Management would be multiple-use and have sustained yield. The Lacey Act of 1990 prohibits the transport of live or dead wild animals (parts or whole) across state lines without a permit. The Surface Mining Control and Reclamation Act of 1977 (SMCRA) regulates the restoration of surface coal mines. The Price-Anderson Act promotes nuclear power by limiting the liability of the owner of a power plant and the government in the event of a major accident.

CITES (Convention on International Trade in Endangered Species of Wild Fauna and Flora) is a 1973 international treaty signed by most world nations that limits and prevents the sale and transportation of endangered species. The intent here was to ensure that international trade of animal and plant products would not cause the rapid decline or extinction of a species. The international shipping and sale of ivory would be banned under this treaty, due to its negative impact on African Elephant populations.

Sustainability is often defined as the ability to endure. This definition can be applied to organisms and ecosystems as well as societies and economies. The 2005 World Summit on Social Development identified the three pillars of sustainability as economic development, social development and environmental protection. The goal of sustainability is to balance human needs (economic and social) with environmental needs. Put another way, sustainability improves the quality of human life without causing environmental degradation.

Some actions that promote sustainability, or as the very least are less wasteful of natural resources, include using renewable energies (e.g., wind and solar power), conserving water, following the three R’s (i.e., reuse, reduce and recycle), and protecting wildlife and biodiversity. Deforestation refers to the practice of cutting down trees in an unsustainable manner. There are ways to sustainably harvest trees which are considered renewable resources, but they must be managed carefully.

A "tragedy of the commons" occurs when people exploit natural resources at a rate that is optimally profitable for the individual with no regard to the long-term sustainability or future profit of the resource. Abalone were harvested to near extinction in California because hundreds of individual fishermen were harvesting at a rate that was most profitable to themselves rather than a rate that would be collectively sustainable. Commercial harvest bans and stringent sport regulations are examples of government tackling issues associated with the tragedy of the commons. 

Until the late nineteenth century, environmental law had a heavy focus on westward expansion and increased land use. This trend was largely fueled by the potential wealth from agricultural activity and harvesting wildlife, timber, and minerals in a region that was largely unsettled and had vast natural resources. Since resources were still quite abundant, conservation was a lower priority than expansion at the time. The Homestead Acts ensured that people of all socioeconomic standing were given equal opportunity to settle the western United States. 

The second wave of U.S. environmental law shifted the focus from westward expansion to conservation of wilderness areas for future use and enjoyment. By this time in history, the western United States had become largely settled and conservation of resources became a higher priority. Air quality had not yet become an issue of concern and remained this way until the middle of the twentieth century when the automobiles and subsequent pollution became more commonplace in the American landscape.