Legislative action has also been sought, with considerable success. The scope of legislation has expanded, as areas once considered of marginal value, such as the polar regions, temperate wetlands, and tropical rain forests, are included in environmental planning. Although varying in scope and stringency, land-use laws are now in force in most of the United States. The National Environmental Policy Act of 1969 requires that federal agencies file statements assessing the environmental impact of proposed projects (see environmental impact statement). Agencies such as the Army Corps of Engineers and the Nuclear Regulatory Commission must now subject their land-use proposals to the Environmental Protection Agency and therefore to public scrutiny. This requirement, along with other legislation empowering citizens to sue industry and government for failure to comply with air pollution and water pollution standards, has profoundly affected land-use decisions. Although conservatives sometimes criticize legislation for the time-consuming and costly obligations it places on private business, environmental activists argue that the act promotes only a modest level of conservation.