T he Endangered Species Act (ESA; P.L. 93-205 , 87 Stat. 884. 16 U.S.C. §§1531-1544) frequently receives significant congressional attention. It offers comprehensive protection for species identified as endangered or threatened with extinction. Over the years, the power of this protection has ignited calls for greater bounds on this power, as well as assertions of its lax implementation. The following discussion provides an overview and background on the various features of the ESA that contribute to its legal stature and yet spark an ongoing debate over its implementation. The ESA is a comprehensive attempt to provide legal protection to identified species and to consider habitat protection as an integral part of that effort. It is administered primarily by the Fish and Wildlife Service (FWS) for terrestrial and freshwater species, but also by the National Marine Fisheries Service (NMFS) for certain marine species. Under the ESA, individual species of plants and animals (both vertebrate and invertebrate) can be listed as either "endangered" or "threatened" according to assessments of the risk of their extinction. Once a species is listed, powerful legal tools are available to aid the recovery of the species and to protect its habitat. Among these legal tools are the ESA's prohibition of unpermitted "take" (e.g., killing, capturing, or harming) of endangered species and its requirement that agencies, in consultation with FWS or NMFS as applicable, ensure that their actions are not likely to jeopardize the continued existence of listed species or result in destruction or adverse modification of critical habitat. (See "Take" and " Critical Habitat ," below.) As of August 24, 2016, a total of 2,266 species of animals and plants had been listed as either endangered or threatened; 1,593 of these species occur in the United States and its territories, and the remainder occur only in other countries. Of the U.S. species, 1,156 are covered by recovery plans. The ESA was passed in 1973, but was preceded by simpler acts to conserve species in 1966 and 1969. It has been amended on numerous occasions since then: 1976, 1977, 1978, 1979, 1980, 1982, 1988, and 2003. The authorization for funding under the ESA expired on October 1, 1992, although Congress has appropriated funds in each succeeding fiscal year. ESA prohibitions and penalties remain in effect regardless of appropriations. A stated purpose of the ESA is to "provide a means whereby the ecosystems upon which endangered species and threatened species depend may be conserved." While the ESA plays an important role in protecting species, it also can become a surrogate battleground in debates whose primary focus is the allocation of scarce or diminishing lands, waters, or resources. The surrogate role is especially likely because other laws often lack the strict substantive provisions that Congress included in the ESA (see " Major Provisions " sections, below). There can be economic interests on multiple sides of some vanishing species issues. Like the miners' canaries signaling a scarce resource (safe air supply), declining species are often symptoms of resource scarcities and altered ecosystems. Examples of such resource controversies include the Tellico Dam (hydropower development and construction jobs versus farmland protection and tribal graves, as well as the endangered snail darter); and Northwest timber harvest (protection of logging jobs and communities versus commercial and sport fishing, recreation, and ecosystem protection, as well as salmon and spotted owls). The worldwide debate over global climate change (fossil fuels, carbon dioxide emission levels, shoreline erosion, melting glaciers, traditional jobs, etc.) has found an avatar in the polar bear. Tensions over the ESA have increased as species have been added to the protected list, and as the greater demands of a growing economy and human population have affected species' habitats. Both Congress and the executive branch have sought to lessen these tensions by, among other things, tailoring application of the ESA for particular circumstances. The ESA's critics contend that neither the ESA nor administrative efforts go far enough in accommodating needs other than species conservation, while the ESA's defenders counter that it only balances what they see as an inherent bias toward development in other governmental laws and policies. Debate on the ESA splits largely along demographic lines. While most demographic groups support species conservation to some degree, that support is stronger among urban and suburban populations and less so in rural areas, and is stronger among those along the coasts and less so in central and mountain states. Sport hunters and anglers seem divided on the issue. Native Americans, as a group often dependent on natural resources (e.g., fish), are frequently involved in ESA issues and often support the survival of listed species. Groups opposing strong protections for listed species usually assert that jobs will be lost if conservation measures are stringent, but those seeking strong protections often claim that jobs will be lost if they are not. It is also noteworthy that, while the debate often centers on jobs and biology, people on both sides claim ethical support for their positions, and many religious groups participate in the debate. In addition, some industries (e.g., logging and land development) generally see the ESA as a serious problem, while others (e.g., some commercial fishing and many recreation interests) see it as generally supporting their interests. There is a difference between the statutory authority to carry out an action and the authorization of appropriations within a statute. The ESA contains both statutory authority for certain activities and a provision authorizing approp riations. Section 15 (16 U.S.C. §1542) is the provision authorizing appropriations—through FY1992. Even though Congress has continued to appropriate funding for ESA, the following questions are sometimes raised: (1) are the act's various prohibitions and authorities still in effect; (2) what are the House and Senate rules concerning appropriating in the absence of a current authorization; and (3) what would be the effect of a failure to appropriate funds for the agencies (primarily for FWS and NMFS, but also Coast Guard, and Secretaries of Agriculture and Treasury) to carry out their responsibilities under the ESA? Because the authorization for appropriations expired in FY1992, it is sometimes said that the ESA is not authorized. However, that does not mean that the agencies lack authority to conduct actions (Sections 4, 6-8, 10, and 11; 16 U.S.C. §§1533, 1535-1537, 1539 and 1540), or that prohibitions within the act are no longer enforceable (Section 9; 16 U.S.C. §1538). Those statutory provisions continue to be law, even if no money were appropriated. The expiration of a provision authorizing appropriations does not end the statutory obligations created by that law. The U.S. Supreme Court has long held that "the mere failure of Congress to appropriate funds, without further words modifying or repealing, expressly or by clear implication, the substantive law, does not in and of itself defeat a Government obligation created by statute." Moreover, Section 11(g) (16 U.S.C. §1540(g)) "allows any citizen to commence a civil suit on his own behalf" on various broad, specified provisions of the act. This option would still be available, regardless of agency funding. Consequently, persons carrying out acts prohibited by ESA might still face citizen suits, even if FWS or NMFS were temporarily unable to carry out their enforcement responsibilities due to lack of funds. The possibility of citizen suits could have the potential to dissuade many parties from carrying out such prohibited acts. Both the House and Senate have long-standing internal rules that distinguish between authorizations and appropriations and provide for the separate consideration of legislation containing these types of provisions. This distinction, however, exists for the convenience of Congress and does not affect a measure's statutory force when enacted into law. Either chamber can choose to observe or waive its rules during the course of the legislative process. Clause 2 of House Rule XXI prohibits consideration of measures or amendments that contain unauthorized appropriations. Further, clause 5 of House Rule XXII prohibits consideration of conference reports containing unauthorized appropriations. House rules additionally prohibit appropriations in legislation not reported by the Committee on Appropriations (Rule XXI, clause 4), amendments thereto (Rule XXI, clause 4), or conference reports (Rule XXII, clause 5). These rules are enforced via points of order on the floor. The House Rules Committee, however, may report a special rule that sets procedural parameters for the consideration of an appropriations measure. This can include the waiver of rules prohibiting unauthorized appropriations for any specified floor amendments, as well as the measure itself. Special rules can also waive points of order against provisions in a conference report on an appropriations measure. In order for these waivers to occur, the House must adopt a special rule prior to consideration of the measure or conference report. Senate rules also distinguish between authorizations and appropriations and prohibit unauthorized appropriations in both committee and floor amendments, except in specified circumstances (Rule XVI, paragraphs 2 and 4). This prohibition does not apply to conference reports. This rule is enforced via points of order during consideration, but its application may be waived by unanimous consent. The practical effects of a lapse in funding would be mixed from the standpoint of supporters and critics of existing law. Some of the areas which might be affected during the period of the lapse are listed below. (These activities are described in the remainder of the report.)