Opinion for the Court filed by Circuit Judge WALD.
Dissenting Opinion filed by Circuit Judge SENTELLE, with whom SILBERMAN, GINSBURG and KAREN LeCRAFT HENDERSON, Circuit Judges, join.
WALD, Circuit Judge:The 1985 amendments to the Animal Welfare Act (“AWA”) direct the Secretary of Agriculture to “promulgate standards to govern the humane handling, care, treatment, and transportation of animals by dealers, research facilities, and exhibitors.” Pub.L. No. 99-198, § 1752, 99 Stat. 1354,1645 (1985) (codified at 7 U.S.C. § 2143(a) (1994)). They further provide that such standards “shall include minimum requirements” for, inter alia, “a physical environment adequate to promote the psychological well-being of primates.” Id. Pursuant to this authority, the United States Department of Agriculture (“USDA”) issued regulations for primate dealers, exhibitors, and research facilities that included a small number of mandatory requirements and also required the regulated parties to “develop, document, and follow an appropriate plan for environment enhancement adequate to promote the psychological well-being of nonhuman primates. The plan must be in accordance with the currently accepted professional standards as cited in appropriate professional journals or reference guides, and as directed by the attending veterinarian.” 9 C.F.R. § 3.81 (1997). Although these plans must be made available to the USDA, the regulated parties are not obligated to make them available to members of the public. See id.
The individual plaintiffs, Roseann Circelli, Mary Eagan, and Marc Jurnove,1 challenge these regulations on the ground that they violate the USDA’s statutory mandate under the AWA and permit dealers, exhibitors, and research facilities to keep primates under inhumane conditions. The individual plaintiffs allege that they suffered aesthetic injury during their regular visits to animal exhibitions when they observed primates living under such conditions.2 A divided panel of this *429court held that all of the plaintiffs lacked constitutional standing to pursue their claims. See Animal Legal Defense Fund, Inc. v. Glickman, 130 F.3d 464, 466 (D.C.Cir.1997). This court subsequently vacated that judgment and granted rehearing in banc.
We hold that Mr. Jurnove, one of the individual plaintiffs, has standing to sue. Accordingly, we need not pass on the standing of the other individual plaintiffs. See Mountain States Legal Found. v. Glickman, 92 F.3d 1228, 1232 (D.C.Cir.1996) (“For each claim, if constitutional and prudential standing can be shown for at least one plaintiff, we need not consider the standing of the other plaintiffs to raise that claim.”). We leave consideration of the merits of the individual plaintiffs’ case to a future panel of this court to be selected by the usual means.
I. Background
A. Marc Jurnove’s Affidavit
Mr. Jurnove’s affidavit is an uncontested statement of the injuries that he has suffered to his aesthetic interest in observing animals living under humane conditions. See Animal Legal Defense Fund, Inc. v. Glickman, 943 F.Supp. 44, 49 (D.D.C.1996) (granting summary judgment to plaintiffs on all legal claims except one that plaintiffs have not appealed; defendants did not allege any genuine disputes of material fact, but instead moved only to dismiss for lack of standing).
For his entire adult life, Mr. Jurnove has “been employed and/or worked as a volunteer for various human and animal relief and rescue organizations.” Jurnove Affidavit 113. “By virtue of [his] training in wildlife rehabilitation and [his] experience in investigating complaints about the treatment of wildlife, [he is] very familiar with the needs of and proper treatment of wildlife.” Id. ¶ 6. “Because of [his] familiarity with and love of exotic animals, as well as for recreational and educational purposes and because [he] appre-ciatefs] these animals' beauty, [he] enjoy[s] seeing them in various zoos and other parks near [his] home.” Id. ¶ 7.
Between May 1995 and June 1996, when he filed his affidavit, Mr. Jurnove visited the Long Island Game Farm Park and Zoo (“Game Farm”) at least nine times. Throughout this period, and since as far back as 1992, the USDA has not questioned the adequacy of this facility’s plan for the psychological well-being of primates.
Mr. Jurnove’s first visit to the Game Farm, in May 1995, lasted approximately six hours. See id. While there, Mr. Jurnove saw many animals living under inhumane conditions. For instance, the Game Farm housed one primate, a Japanese Snow Macaque, in a cage “that was a distance from and not in view of the other primate cages.” Id. ¶ 14. “The only cage enrichment device this animal had was an unused swing.” Id. Similarly, Mr. Jurnove “saw a large male chimpanzee named Barney in a holding area by himself. He could not see or hear any other primate.” Id. ¶ 8. Mr. Jurnove “kn[e]w that chimpanzees are very social animals and it upset [him] very much to see [Barney] in isolation from other primates.” Id. The Game Farm also placed adult bears next to squirrel monkeys, although Jurnove saw evidence that the arrangement made the monkeys frightened and extremely agitated. See id. ¶ 11.
The day after this visit, Mr. Jurnove began to contact government agencies, including the USDA, in order to secure help for these animals. Based on Mr. Jurnove’s complaint, the USDA inspected the Game Farm on May 3, 1995. According to Mr. Jurnove’s uncontested affidavit, however, the agency’s resulting inspection report “states that [the USDA inspectors] found the facility in compliance with all the standards.” Id. ¶ 18. Mr. Jur-nove returned to the Game Farm on eight more occasions to observe these officially legal conditions.
On July 17, 18, and 19, 1995, he found “virtually the same conditions” that allegedly caused him aesthetic injury during his first visit to the Game Farm in May. Id. ¶20. For instance, Barney, the chimpanzee, and Samantha, the Japanese Snow Macaque, were still alone in their cages. See id. This *430time, Mr. Jurnove documented these conditions with photographs and sent them to the USDA. See id. ¶¶ 19-20. Nevertheless, the responding USDA inspectors found only a few violations at the Game Farm; they reported “nothing” about many of the conditions that concerned Mr. Jurnove and that he had told the agency about, such as “the fact that numerous primates were being housed alone” and the lack of adequate stimulation in their cages. Id. ¶ 21.
Mr. Jurnove devoted two trips in August and one in September to “videotaping the conditions that the inspection missed,” and on each trip he found that the inhumane conditions persisted. Id. ¶¶ 22-28. At the end of September, the USDA sent three inspectors to the Game Farm in response to Mr. Jurnove’s continued complaints and reportage; they found violations, however, only with regard to the facility’s fencing. See id. ¶ 29.
Mr. Jurnove returned to the Game Farm once more on October 1, 1995. Indeed, he only stopped his frequent visits when he became ill and required major surgery. See id. ¶ 30. After his health returned, Mr. Jur-nove visited the Game Farm in April 1996, hoping to see improvements in the conditions that he had repeatedly brought to the USDA’s attention. He was disappointed again; “the animals [were] in literally the same conditions as [he] had seen them over the summer of 1995.” . Id. ¶ 33. Mr. Jur-nove’s resulting complaints prompted the USDA to inspect the Game Farm in late May 1996. For the fourth time, the agency found the facility largely in compliance, with a few exceptions not relevant to the plaintiffs’ main challenge in this ease. See id. ¶ 42. In June 1996, Mr. Jurnove filed the affidavit that is the basis of his claim here. He concluded this affidavit by stating his intent to “return to the Farm in the next several weeks” and to “continue visiting the Farm to see the animals there.” Id. ¶ 43.
B. The Plaintiffs’ Complaint
The plaintiffs’ complaint elaborates a two-part legal theory based on the factual allegations in the individual plaintiffs’ affidavits. First, the plaintiffs allege that the AWA requires the USDA to adopt specific, minimum standards to protect primates’ psychological well-being, and the agency has failed to do so. See, e.g., First Amended Complaint ¶ 97 (“In issuing final Part 3 regulations, USDA violated its statutory obligation [under 7 U.S.C. § 2143(a)(2)(B) ] to set standards ‘for a physical environment adequate to promote the psychological well-being of primates,’ and instead delegated this responsibility to regulated entities by requiring that regulated entities devise ‘plans’ for this purpose.”); id. ¶ 106 (“Instead of issuing the standards on this topic, USDA’s regulation [at 9 C.F.R. § 3.81] simply states that the ‘plans’ must be in accordance with currently accepted professional standards.”); id. ¶ 107 (“By providing that animal exhibitors and other regulated entities shall develop their own ‘plans’ for a physical environment adequate to promote the psychological well-being of non-human primates, USDA has failed to satisfy the statutory requirement that it set the ‘minimum’ standards.”).
Second, the plaintiffs contend that the conditions that caused Mr. Jurnove aesthetic injury complied with current USDA regulations, but that lawful regulations would have prohibited those conditions and protected Mr. Jurnove from the injuries that he describes in his affidavit. See id. ¶ 53 (“Marc Jurnove has been and continues to be injured by USDA’s failure to issue and implement standards for a physical environment adequate to promote the psychological well-being of primates because this harms the nonhuman primates he sees at the Long Island Game Farm and Zoo which in turn caused and causes him extreme aesthetic harm and emotional and physical distress.”); id. (“[B]ecause USDA regulations permit the nonhuman primates in zoos, such as the Long Island Game Farm and Zoological Park to be housed in isolation, Marc Jurnove was exposed to and will be exposed in the future to behaviors exhibited by these animals which indicate the psychological debilitation caused by social deprivation. Observing these behaviors caused and will cause Marc Jurnove personal distress and aesthetic and emotional injury.”); id. ¶ 58 (“Marc Jurnove experienced and continues to experience *431physical and mental distress when he realizes that he, by himself, is powerless to help the animals he witnesses suffering when such, suffering derives from or is traceable to the improper implementation and enforcement of the Animal Welfare Act by USDA.”).3
C. Procedural History
The United States District Court, Judge Charles R. Richey, held that the individual plaintiffs had standing to sue, finding in their favor on a motion for summary judgment. See 943 F.Supp. at 54-57.4 On the merits, the district court held that 9 C.F.R. § 3.81 violates the Administrative Procedure Act (“APA”) because it fails to set standards, including minimum requirements, as mandated by the AWA; that the USDA’s failure to promulgate standards for a physical environment adequate to promote the psychological well-being of primates constitutes agency action unlawfully withheld and unreasonably' delayed in violation of the APA; and that the USDA’s failure to issue a regulation promoting the social grouping of nonhuman primates is arbitrary, capricious, and an abuse of discretion in violation of the APA. See id. at 59-61.
A split panel of this court held that none of the plaintiffs had standing to sue and accordingly did not reach the merits of their complaint. See 130 F.3d at 466. This court granted rehearing in banc, limited to the question of Marc Jurnove’s standing.
II. Analysis
“The question of standing involves both constitutional limitations on federal-court jurisdiction and prudential limitations on its exercise.” Bennett v. Spear, 520 U.S. 154, 117 S.Ct. 1154, 1161, 137 L.Ed.2d 281 (1997) (citation and quotation marks omitted). .To meet the “case or controversy requirement of Article III, a plaintiff must demonstrate: (1) that she has suffered “injury in fact;” (2) that the injury is “fairly traceable” to the defendant’s actions; and (3) that a favorable judicial ruling will “likely” redress the plaintiffs injury. Id.; see also Lujan v. Defenders of Wildlife, 504 U.S. 555, 560-61, 112 S.Ct. 2130, 119 L.Ed.2d 351 (1992). In addition, the Supreme Court has recognized prudential requirements for standing, including “that a plaintiffs grievance must arguably fall within the zone of interests protected or regulated by the statutory provision or constitutional guarantee invoked in the suit.” Bennett, 117 S.Ct. at 1161.
We find that Mr. Jurnove’s allegations fall well-within these requirements.
A. Injury in Fact
Mr. Jurnove’s allegations solidly establish injury in fact. As his affidavit indicates, Mr. Jurnove “enjoy[s] seeing [animals] in various zoos and other parks near [his] home” “[b]eeause of [his] familiarity with and love of exotic animals, as well as for recreational and educational purposes and because [he] appreciate^] these animals’ beauty.” Jurnove Affidavit ¶ 7. He decided to tour the primate cages at the Game Farm “in furtherance of [his] appreciation for exotic animals and [his] desire to observe and enjoy them.” Id. During this tour and the ones that followed, Mr. Jurnove suffered direct, concrete, and particularized injury to this aesthetic interest in observing animals living under humane conditions. At this particular zoo, which he has regularly visited and plans to keep visiting, he saw particular animals enduring inhumane treatment. He developed an interest, moreover, in seeing these particular animals living under humane treat*432ment. As he explained, “[w]hat I observed [at the Game Farm] was an assault on my senses and greatly impaired my ability to observe and enjoy these captive animals.” Id. ¶ 17 (emphasis added). “I want to observe, study, and enjoy these animals in humane conditions.” Id. ¶ 43.
Simply put, Mr. Jurnove has alleged far more than an abstract, and uncognizable, interest in seeing the law enforced. See Allen v. Wright, 468 U.S. 737, 754, 104 S.Ct. 3315, 82 L.Ed.2d 556 (1984) (“This Court has repeatedly held that an asserted right to have the Government act in accordance with law is not sufficient, standing alone, to confer jurisdiction on a federal court.”); Schlesinger v. Reservists Committee to Stop the War, 418 U.S. 208, 223 n. 13, 94 S.Ct. 2925, 41 L.Ed.2d 706 (1974) (rejecting standing of plaintiffs who alleged nothing but “the abstract injury in nonobservanee of the Constitution”); Humane Society v. Hodel, 840 F.2d 45, 51-52 (D.C.Cir.1988). To the contrary, Mr. Jurnove has made clear that he has an aesthetic interest in seeing exotic animals living in a nurturing habitat, and that he has attempted to exercise this interest by repeatedly visiting a particular animal exhibition to observe particular animals there. This interest was allegedly injured, however, when Mr. Jurnove witnessed the actual living conditions of the primates described and named in his affidavit. It is, of course, quite possible that many other people might visit the same zoo, observe the same animals there, and suffer similar injuries upon seeing these animals living under inhumane conditions. But the fact that many may share an aesthetic interest does not make it less cognizable, less “distinct and palpable.” Allen, 468 U.S. at 751, 104 S.Ct. 3815 (citation and quotation marks omitted); Clinton v. City of New York, — U.S. -,-, 118 S.Ct. 2091, 2101-02, 141 L.Ed.2d 393 (1998) (“[It is a] self-evident proposition that more than one party may have standing to challenge a particular action or inaction. Once it is determined that a particular plaintiff is harmed by the defendant, and that the harm will likely be redressed by a favorable decision, that plaintiff has standing — regardless of whether there are others who would also have standing to sue.”); FEC v. Akins, — U.S. -, -, 118 S.Ct. 1777, 1786, 141 L.Ed.2d 10 (1998) (“Often the fact that an interest is abstract and the fact that it is widely shared go hand in hand. But their association is not invariable, and where a harm is concrete, though widely shared, the Court has found ‘injury in fact.’”); United States v. SCRAP, 412 U.S. 669, 688, 93 S.Ct. 2405, 37 L.Ed.2d 254 (1973) (“To deny standing to persons who are in fact injured simply because many others are also injured, would mean that the most injurious and widespread Government actions could be questioned by nobody.”); Sierra Club v. Morton, 405 U.S. 727, 734, 92 S.Ct. 1361, 31 L.Ed.2d 636 (1972) (“Aesthetic and environmental well-being, like economic well-being, are important ingredients of the quality of life in our society, and the fact that particular environmental interests are shared by the many rather than the few does not make them less deserving of legal protection through the judicial process.”).
The Supreme Court has repeatedly made clear that injury to an aesthetic interest in the observation of animals is sufficient to satisfy the demands of Article III standing. Defenders of Wildlife states explicitly that “the desire to use or observe an animal species, even for purely esthetic purposes, is undeniably a cognizable interest for purpose of standing.” 504 U.S. at 562-63, 112 S.Ct. 2130 (emphasis added). Similarly, in Japan Whaling Association v. American Cetacean Society, 478 U.S. 221, 106 S.Ct. 2860, 92 L.Ed.2d 166 (1986), the Court found that the plaintiffs had “undoubtedly ... alleged a sufficient ‘injury in fact’ in that the whale watching and studying of their members will be adversely affected by continued whale harvesting,” id. at 231 n. 4, 106 S.Ct. 2860 (citing Sierra Club v. Morton, 405 U.S. 727, 92 S.Ct. 1361, 31 L.Ed.2d 636 (1972); United States v. SCRAP, 412 U.S. 669, 93 S.Ct. 2405, 37 L.Ed.2d 254 (1973)); see also Animal Legal Defense Fund, Inc. v. Espy (“ALDF I”), 23 F.3d 496, 505 (D.C.Cir.1994) (Williams, J., concurring in part and dissenting in part) (“Japan Whaling Association and Defenders of Wildlife clearly recognize people’s affirmative aesthetic interest in viewing animals enjoying their natural habitat.”).
*433The key requirement, one that Mr. Jur-nove clearly satisfies, is that the plaintiff have suffered his injury in a personal and individual way—for instance, by seeing with his own eyes the particular animals whose condition caused him aesthetic injury. As the Supreme Court noted in Defenders of Wildlife, “[i]t is clear- that the person who observes or works with a particular animal threatened by a federal decision is facing perceptible harm.” 504 U.S. at 566, 112 S.Ct. 2130 (emphasis added); see also id. at 582 & 584 n. 2, 112 S.Ct. 2130 (Stevens, J., concurring in the judgment) (“In my opinion a person who has visited the critical habitat of an endangered species, has a professional interest in preserving the species and its habitat, and intends to revisit them in the future has standing to challenge agency action that threatens their destruction.... [Respondents would not be injured by the challenged projects if they had not visited the sites or studied the threatened species and habitat.”) (emphasis added); Animal Legal Defense Fund, Inc. v. Espy (“ALDF II"), 29 F.3d 720, 726 (D.C.Cir.1994) (Mikva, C.J., concurring) (“Had the [plaintiffs] challenging the Secretary’s regulations alleged an interest in protecting the well-being of specific laboratory animals (an interest predating this litigation), I think [the plaintiffs] would have had standing to challenge those regulations for providing insufficient protection to the animals.”) (emphasis added); Didrickson v. United States Dep’t of the Interior, 982 F.2d 1332, 1340-41 (9th Cir.1992) (finding standing where plaintiffs “declared that they have observed, enjoyed and studied sea otters in specific areas in Alaska.... The [plaintiffs] are concerned with action harming sea otters in Alaska, where [they] live and in particular areas that they frequent, unlike the de-clarants in Defenders of Wildlife.") (emphasis added); cf. Defenders of Wildlife, 504 U.S. at 567, 112 S.Ct. 2130 (“It goes beyond the limit, however, and into pure speculation and fantasy, to say that anyone who observes or works with an endangered species, anywhere in the world, is appreciably harmed by a single project affecting some portion of that species with which he has no more specific connection.”).
This court’s precedent, moreover, specifically recognizes that people have a cognizable interest in “view[ing] animals free from ... ‘inhumane treatment.’ ” Humane Society v. Babbitt, 46 F.3d 93, 99 n. 7 (D.C.Cir.1995) (quoting Animal Welfare Institute v. Kreps, 561 F.2d 1002, 1007 (D.C.Cir.1977)); see also ALDF I, 23 F.3d at 505 (Williams, J., concurring in part and dissenting in part) (“Our own cases have indicated a recognition of people’s interest in seeing animals free from inhumane treatment.”). In Animal Welfare Institute v. Kreps, 561 F.2d 1002 (D.C.Cir.1977), the plaintiff organizations alleged, inter alia, an interest in “enjoyfing] Cape fur seals alive in their natural habitat under conditions in which the animals are not subject to ... inhumane treatment,” id. at 1007 (citation and quotation marks omitted). This court held that these plaintiffs’ aesthetic interests satisfied the requirements of standing. See id. at 1007-10.5 Similarly, Humane Society v. Hodel found standing based on a complaint “that the existence of hunting on wildlife refuges forces Society members to *434witness animal corpses and environmental degradation, in addition to depleting the supply of animals and birds that refuge visitors seek to view,” 840 F.2d at 52. As this Court noted, “[t]hese are classic aesthetic interests, which have always enjoyed protection under standing analysis.” Id.6
The Ninth Circuit has similarly recognized an aesthetic interest in observing animals living under humane conditions. In Fund for Animals, Inc. v. Lujan, 962 F.2d 1391 (9th Cir.1992), the plaintiffs alleged aesthetic injuries stemming from the mistreatment of bison, who were subject to a population management plan that operated by shooting animals who strayed outside the boundaries of Yellowstone. In finding standing, the court observed “that the Fund’s members had standing to sue because of the psychological injury they suffered from viewing the killing of the bison in Montana. Mr. Pacelle testified that several Fund members had been emotionally harmed when they saw bison ‘who were just standing outside the boundary of the park shot and crumbled [sic] to them feet.’ ” Id. at 1396 (quoting testimony and citing Humane Society v. Hodel, 840 F.2d 45 (D.C.Cir.1988)).7
Analogously, the Supreme Court and this circuit have frequently recognized the injury in fact of plaintiffs who suffered aesthetic injury stemming from the condition and quality, or despoliation, of an environmental area that they used. In Mountain States Legal Foundation, for instance, the plaintiffs asserted injury flowing from government action that would allegedly make the Kootenai National Forest more vulnerable to forest fire. This court found an “aesthetic and environ*435mental interest[ ] in having such areas free of devastating forest fire ... clearly sufficient for Article III standing.” 92 F.3d at 1234. Similarly, in Montgomery Environmental Coalition v. Costle, 646 F.2d 568 (D.C.Cir.1980), the plaintiffs challenged the Environmental Protection Agency’s (“EPA’s”) regulation of “two sewage treatment plants that discharge pollutants into the Potomac River and its tributaries,” id. at 573. They “profess[ed] an interest in the preservation and enhancement of the natural environment situated along the Potomac estuary,” id. at 576, and alleged that the EPA had issued “permits too lax to protect the water quality of the Potomac,” id. at 573. This court found standing. See id. at 578. Committee for Auto Responsibility v. Solomon, 603 F.2d 992 (D.C.Cir.1979) (per curiam), involved “a challenge to the leasing by the General Services Administration (GSA) of the Great Plaza area of the Federal Triangle in Washington, D.C., for use as a parking facility for employees of federal agencies,” id. at 996. Plaintiffs, “two organizations whose purposes include improvement of the quality of the environment, together with three individuals who live and attend school in the District of Columbia,” id. at 997, successfully established injury in fact based on allegations that they were “affected by noise, air pollution and congestion from vehicles utilizing the Great Plaza parking lot,” id. at 998. In Lujan v. National Wildlife Federation, 497 U.S. 871, 110 S.Ct. 3177, 111 L.Ed.2d 695 (1990), the plaintiffs challenged federal action that allegedly “threatened] the aesthetic beauty and wildlife habitat potential” of the South Pass-Green Mountain area of Wyoming, id. at 886, 110 S.Ct. 3177 (citation and quotation marks omitted). The Supreme Court stated that it had “no doubt” that this threat could constitute aesthetic injury under Article III, noting that “[t]he only issue” was whether the individual plaintiffs in the case had established that their interests “were actually affected.” Id.; see also id. at 901 n. 2, 110 S.Ct. 3177 (Blackmun, J., dissenting) (arguing that plaintiffs had established then-standing and observing that “[a Bureau of Land Management] Mineral Report issued June 17, 1982, concluded that mining and associated activities ‘could have an adverse impact on crucial moose habitat, deer habitat, some elk habitat, and a variety of small game and bird species. Improvements at campgrounds, as well as land in the immediate vicinity, could either be damaged or destroyed.’ ”) (citation omitted).
Indeed, Humane Society v. Hodel, which recognized an aesthetic interest in seeing animals living under humane conditions, explicitly acknowledged the usefulness of analogizing such an aesthetic interest to a plaintiffs interest in the condition of an environmental area that he uses. That case drew on our opinion in National Wildlife Federation v. Hodel, 839 F.2d 694 (D.C.Cir.1988), which held that a wildlife organization had standing to challenge regulations that allegedly threatened to degrade the environment, see id. at 703-16. The Humane Society court noted that the two cases involved “strikingly analogous” injuries, explaining: “There the National Wildlife Federation’s standing rested in part on the aesthetic injuries to those members who complained of viewing degraded landscapes, and here the Humane Society’s standing similarly rests on the aesthetic injuries to members who complain of viewing the despoliation of animals.” 840 F.2d at 52 (citations omitted).
In the environmental context, too, however, plaintiffs must establish that they have actually used or plan to use the allegedly degraded environmental area in question. It is this failure to show such direct use that has resulted in the denial of standing in several high-profile environmental cases. For instance, the injury alleged in Sierra Club v. Morton would have been “incurred entirely by reason of the change in the uses to which Mineral King [Valley] will be put, and the attendant change in the aesthetics and ecology of the area.” 405 U.S. at 734, 92 S.Ct. 1361. Specifically, the Sierra Club alleged that the challenged development of the Valley “ ‘would destroy or otherwise adversely affect the scenery, natural and historic objects and wildlife of the park and would impair the enjoyment of the park for future *436generations.’” Id. (emphasis added).8 The Supreme Court “[did] not question that this type of harm may amount to an ‘injury in fact’ sufficient to lay the basis for standing under § 10 of the APA.” Id. However, haying found “a cognizable interest,” the Court held that the Sierra Club had not established that its members were “among the injured.” Id. at 734-35, 92 S.Ct. 1361. As the Court explained, “[t]he impact of the proposed changes in the environment of Mineral King will not fall indiscriminately upon every citizen. The alleged injury will be felt directly only by those who use Mineral King and Sequoia National Park, and for whom the aesthetic and recreational values of the area will be lessened by the highway and ski resort.” Id. at 735, 92 S.Ct. 1361 (emphasis added). “The Sierra Club failed to allege that it or its members would be affected in any of their activities or pastimes by the Disney development. Nowhere in the pleadings or affidavits did the Club state that its members use Mineral King for any purpose, much less that they use it in any way that would be significantly affected by the proposed actions of the respondents.” Id.
Similarly, the plaintiffs in Lujan v. National Wildlife Federation lacked standing because their affidavits “state[d] only that one of [the Federation’s] members use[d] unspecified portions of an immense tract of territory, on some portions of which mining activity has occurred or probably will occur by virtue of the governmental action,” rather than making clear that a plaintiff used the smaller area of land that was allegedly threatened. 497 U.S. at 889, 110 S.Ct. 3177. In contrast, a plaintiff in Mountain States Legal Foundation, who established injury in fact based on aesthetic injury, stated “that he use[d] the forest [in question] for, inter alia, hiking, hunting, camping, fishing, observing wildlife, finding solitude, and picking berries.” 92 F.3d at 1234 (citations omitted). The plaintiffs in Committee for Auto Responsibility, who also successfully established their injury in fact, “claimfed] that they or their members live in or near the District of Columbia and regularly travel to educational, cultural and recreational facilities within the immediate vicinity of the Great Plaza [parking lot].” 603 F.2d at 998; see also Montgomery Environmental Coalition, 646 F.2d at 578 (“[The Coalition’s] members include residents of Maryland, Virginia, and the District of Columbia, by whose shores the Potomac River flows. We may take judicial notice of the fact that that river can be seen and smelt from those shores, and even that, as an important source of drinking water, it can be tasted.... Petitioners’ members are users of the Potomac River, and their standing to challenge the Blue Plains and Seneca permits is clear.”).
Other circuits have also recognized injury in fact based on injury to a plaintiffs interest in the quality and condition of an environmental area that he used. In Public Interest Research Group v. Powell Duffryn Terminals, Inc., 913 F.2d 64 (3d Cir.1990), the Research Group’s members “resided in the vicinity of or owned property on or near the Kill Van Kull, or recreated on or near the Kill Van Kull,” id. at 71. They successfully “claimed injury to their aesthetic and recreational interests because the Kill Van Kull [was] polluted.” Id. One member alleged that he “was particularly offended by the brown color and bad odor of the water. He stated that he would birdwatch more frequently and enjoy his recreation on the Kill Van Kull more if the water were cleaner.” Id. In Sierra Club v. Simkins Industries, Inc., 847 F.2d 1109 (4th Cir.1988), the “Sierra Club submitted the affidavit of member John Railey attesting to his interest, as one regularly using and enjoying the Patapsco River and surrounding land, in preserving the environmental integrity of the river,” id. at 1112. Mr. Railey established Article III injury based on an affidavit alleging that:
“ ‘My interest, use or enjoyment of the Patapsco River and surrounding area includes preserving the health, safety and welfare of the river basin, preserving marine life and water integrity within the *437river, and eliminating odorous and unsightly illegal pollution. I regularly hike along the river. My activities and interests with respect to the Patapsco River have been adversely affected physically, aesthetically and emotionally by Simkin’s [sic] Industries’ failure to comply with its NPDES permit and resulting illegal pollution.’ ”
Id. at 1112 n. 3 & 1113 (citation omitted). Friends of the Earth v. Consolidated Rail Corp., 768 F.2d 57 (2d Cir.1985), recognized injury in fact based on the pollution of “Conrail’s A.E. Perlman Yard in Selkirk, New York (Selkirk Yard), a diesel locomotive repair and refueling facility, which discharges treated wastes from its operations through point sources into the Hudson River and South Albany Creek,” id. at 59, where the individual plaintiffs used the Hudson River and lived near its shores, see id. at 61; see also Save Our Community v. U.S. Environmental Protection Agency, 971 F.2d 1155, 1157, 1161 (5th Cir.1992) (per curiam) (finding injury in fact where plaintiff alleged aesthetic injury stemming from “the draining of several ponds on the site of a proposed expansion of a 73-acre landfill”); United States v. Metropolitan St. Louis Sewer District, 883 F.2d 54, 56 (8th Cir.1989) (“Missouri Coalition and two of its named members allege that many of the 25,000 members visit, cross, and frequently observe the bodies of water identified in the United States’ complaint and that from time to time these members use these waters for recreational purposes. They also allege that these interests are adversely affected by the pollution of these waters. These allegations are sufficient to give the Coalition and its members constitutional standing....”); Chesapeake Bay Found. v. American Recovery Co., 769 F.2d 207, 209 (4th Cir.1985) (per curiam) (“[Plaintiffs here ... allege that their members resided in the vicinity of the affected waters and that those members ‘recreate in, on or near, or otherwise use and enjoy’ those waters.”).
These myriad cases recognizing individual plaintiffs’ injury in fact based on affronts to their aesthetic interests in observing animals living in humane habitats, or in using pristine environmental areas that have not been despoiled, articulate a second principle of standing. It has never been the law, and is not so today, that injury in fact requires the elimination (or threatened elimination) of either the animal species or environmental feature in question. In Sierra Club v. Morton, the Sierra Club did not allege that the Mineral King Valley would disappear in the wake of the challenged development, or that the desecration of the Valley would leave the Club’s members with no other, pristine parks that they could conveniently use. See 405 U.S. at 734, 92 S.Ct. 1361. Yet the Supreme Court held that plaintiffs could establish injury in fact based on a decline in the quality and condition of one environmental area that they did use. See id.
To be sure, a number of cases that have recognized standing based on an aesthetic interest in the observation of animals have involved government action that allegedly threatened to diminish the overall supply of an animal species. See Defenders of Wildlife, 504 U.S. at 562, 112 S.Ct. 2130; Japan Whaling Ass’n, 478 U.S. at 231 n. 4, 106 S.Ct. 2860. But there is no case that we know of establishing that the elimination of a species or even the deaths of particular animals is an indispensable element of the plaintiffs’ aesthetic injury, and we see no reason to import such a requirement into our standing doctrine so late in the day. Indeed, the standing cases that do stress the threat of diminished animal populations were those brought under conservation statutes whose mission is to preserve the number of animals in existence. See Defenders of Wildlife, 504 U.S. at 558, 112 S.Ct. 2130 (“[The Endangered Species Act] seeks to protect species of animals against threats to their continuing existence caused by man.”); Japan Whaling Ass’n, 478 U.S. at 225, 106 S.Ct. 2860 (“Because of the [International Whaling Commission’s] inability to enforce its own quota and in an effort to promote enforcement of quotas set by other international fishery conservation programs, Congress passed the Pelly Amendment to the Fisherman’s Protective Act of 1967. Principally intended to preserve and protect North American Atlantic salmon from depletion by Danish fisherman in violation of the ban imposed by the International Convention for the Northwest Atlantic Fisheries, the *438Amendment protected whales as well.”)- It is not surprising, then, that the plaintiffs who brought suit to allege violations of these statutes would emphasize that the challenged agency action threatened to diminish the supply of an animal species, in contravention of the express purpose of those conservation statutes. In contrast, the Animal Welfare Act, with which we deal here, is explicitly concerned with the quality of animal life, rather than the number of animals in existence. It seeks “to promote the psychological wellbeing of primates.” Pub.L. No. 99-198, § 1752, 99 Stat. 1354, 1645 (1985) (codified at 7 U.S.C. § 2143(a) (1994)) (emphasis added). Quite naturally, suits alleging violations of this statute will focus on the conditions under which animals live. Cf. ALDF II, 29 F.3d at 722 (“The primary purpose of the [Federal Laboratory Animal Welfare] Act is to ensure the humane care and treatment of various animals used in research or for exhibition or kept as pets. 7 U.S.C. § 2131. To this end, the Act requires, inter alia, that the Secretary of Agriculture ‘promulgate standards to govern the .humane handling, care, treatment, and transportation of animals by dealers, research facilities, and exhibitors.’ Id. § 2143(a)(1).”). Along these lines, this court has already noted in Animal Welfare Institute, which recognized injury in fact based on an aesthetic interest in seeing animals living under humane conditions, that “[w]here an act is expressly motivated by considerations of humaneness toward animals, who are uniquely incapable of defending their own interests in court, it strikes us as eminently logical to allow groups specifically concerned with animal welfare to invoke the aid of the courts in enforcing the statute.” 561 F.2d at 1007. Moreover, and perhaps more importantly, it does not make sense, as a matter of logic, to suppose that people suffer aesthetic injury from government action that threatens to wipe out an animal species altogether, and not from government action that leaves some animals in a persistent state of suffering. To the contrary, the latter seems capable of causing more serious aesthetic injury than the former.
Mr. Jurnove has adequately alleged injury to an aesthetic interest in observing animals living under humane conditions. His affidavit describes both the animal exhibition that he regularly visits, and the specific animals there whose condition caused Mr. Jurnove injury. It requires no expansion of existing standing doctrine to find that he has established á cognizable injury in fact.
B. Causation
Plaintiffs allege that the AWA, 7 U.S.C. § 2143, requires the USDA to adopt explicit minimum standards to govern the humane treatment of primates, and that the agency did not do so. See First Amended Complaint ¶¶ 97,106,107. They further contend that the conditions that caused Mr. Jurnove injury complied with current USDA regulations, but that lawful regulations would have prohibited those conditions and protected Mr. Jurnove from the injuries that his affidavit describes. See id. ¶¶ 53, 58. We find that these allegations satisfy the causation prong of Article III standing.
As Mr. Jurnove’s affidavit elaborates, he allegedly suffered aesthetic injury upon observing conditions that the present USDA regulations permit. Mr. Jurnove, for instance, “saw a large male chimpanzee named Barney in a holding area by himself. He could not see or hear any other primate.” Jurnove Affidavit ¶8. Mr. Jurnove also “viewed a monkey cage [containing one Japanese Snow Macaque] that was a distance from and not in view of the other primate cages.” Id. ¶ 14. As the plaintiffs observe, see First Amended Complaint ¶¶ 84, 95, 114-17, the housing of these two primates appears to be compatible with current regulations, which state only that “[t]he environment enhancement plan must include specific provisions to address the social needs of nonhuman primates of species known to exist in social groups in nature. Such specific provisions must be in accordance with currently accepted professional standards, as cited in appropriate professional journals or reference guides, and as directed by the attending veterinarian.” 9 C.F.R. § 3.81(a) (emphasis added). Thus, an exhibition may apparently comply with the procedural requirement that this standard creates — by establishing a plan that “address[es]” the social needs of pri*439mates — and still leave a primate caged singly. Similarly, 9 C.F.R. § 3.81(a)(3) provides that “[ijndividually housed nonhuman primates must be able to see and hear nonhuman primates of their own or compatible species unless the attending veterinarian determines that it would endanger their health, safety, or well-being.” Here again, the regulation is structured so that an exhibitor that secured the approval of the veterinarian in its employ could comply with the regulation without actually housing nonhuman primates within the sight or sound of other primates. Contrary to the dissent, see Dissent at 451-52, plaintiffs do not suggest that the regulation is flawed simply because it leaves room for bribery in securing a veterinarian’s consent to an exception; rather, they contend that the regulation gives exhibitors too much leeway to shop around for a compliant veterinarian and that placing such broad and unguarded discretion in the hands of the veterinarian in an exhibitor’s own employ is an insufficient safeguard to protect primate well-being. Whatever the ultimate merits of the plaintiffs’ case, they most definitely assert that the AWA requires minimum standards to prohibit or more rigidly restrict the occasions on which such allegedly inhumane treatment can occur.
Mr. Jurnove’s affidavit also states that “[t]he pen next to the adult bears housed the squirrel monkeys_ I observed the monkeys repeatedly walking over to the door and sniffing and acting very upset when the bears came near.” Jurnove Affidavit ¶ 11. Plaintiffs allege that the current regulations permit the housing of incompatible species next to each other. See First Amended Complaint ¶¶ 46-47. Specifically, these regulations state that “[njonhuman primates may not be housed with other species of primates or animals unless they are eompati-9 C.F.R. § 3.81(a)(3) (emphasis added). This provision does not expressly regulate animals housed next to each other, but in separate cages. But even if section 3.81(a)(3) does apply to the situation that Mr. Jurnove observed, it includes the caveat that “[ejompatibility of nonhuman primates must be determined in accordance with generally accepted professional practices and actual observations, as directed by the attending veterinarian,” thus again permitting wide discretion on the part of the local veterinarian. ble:
Similarly, Mr. Jurnove’s affidavit observes that “[t]he only cage enrichment device [a Japanese Snow Macaque] had was an unused swing.” Jurnove Affidavit ¶ 14. The plaintiffs allege that such a situation is perfectly legal under the present regulations, see First Amended Complaint ¶ 84, which provide only that “[t]he physical environment in the primary enclosures must be enriched by providing means of expressing noninjurious species-typical activities.” 9 C.F.R. § 3.81(b). The regulations do not include any specific requirements governing the particular kind or number of enrichment devices. According to the plaintiffs, providing only a single swing, and one that the primate appears to shun, offends the AWA’s mandate for minimum standards, although it is perfectly compatible with 9 C.F.R. § 3.81(b).9
The USDA’s own actions in this ease further support the plaintiffs’ allegation that the agency’s current regulations allow the conditions that allegedly caused Mr. Jurnove injury. As Mr. Jurnove’s affidavit makes clear, the Game Farm has repeatedly submitted to inspection by the USDA. The allegedly inhumane conditions at the Game Farm have persisted precisely because the USDA in-*440speetors have concluded on the basis of these visits that in every important aspect the conditions at the Game Farm comply with the USDA regulations. If the USDA had found the Game Farm out of compliance with current regulations, or if the governing regulations had themselves been more stringent, the Game Farm’s owners would have been forced (in order to remain in accord with the law) to either alter their practices or go out of business and transfer their animals to exhibitors willing to operate legally; either scenario would protect Mr. Jurnove’s aesthetic interest in observing animals living under humane conditions. Instead, however, the USDA has not questioned the legality of the Game Farm’s plan since 1992. Since May 1995, when Mr. Jurnove began visiting the Game Farm and complaining to the agency, the USDA inspectors have examined, and largely approved, the actual conditions at the facility at least four times. The USDA’s first inspection report “states that [the USDA inspectors] found the facility in compliance with all the standards.” Jurnove Affidavit ¶ 18. Although subsequent inspection reports identify a few conditions that Mr. Jur-nove agrees violate the USDA regulations, the USDA continued — in at least three more inspection reports — to conclude that the Game Farm was in compliance with existing USDA regulations in all other respects, including presumably the existence of a plan that met the regulations’ standards.10 ■
Supreme Court precedent establishes that the causation requirement for constitutional standing is met when a plaintiff demonstrates that the challenged agency action authorizes the conduct that allegedly caused the plaintiffs injuries, if that conduct would allegedly be illegal otherwise. For instance, Simon v. Eastern Kentucky Welfare Rights Organization, 426 U.S. 26, 96 S.Ct. 1917, 48 L.Ed.2d 450 (1976), stated in describing earlier eases that:
The complaint in [Association of] Data Processing [Service Organizations, Inc. v. Camp, 397 U.S. 150, 90 S.Ct. 827, 25 L.Ed.2d 184 (1970),] alleged injury that was directly traceable to the action of the defendant federal official, for it complained of injurious competition that would have been illegal without that action. Accord, Arnold Tours, Inc. v. Camp, 400 U.S. 45, 91 S.Ct. 158, 27 L.Ed.2d 179 (1970); Investment Co. Institute v. Camp, 401 U.S. 617, 620-621, 91 S.Ct. 1091, 28 L.Ed.2d 367 (1971). Similarly, the complaint in Data Processing’s companion case of Barlow v. Collins, 397 U.S. 159, 90 S.Ct. 832, 25 L.Ed.2d 192 (1970), was sufficient because it alleged extortionate demands by plaintiffs’ landlord made possible only by the challenged action of the defendant federal official. See id., at 162-163, 90 S.Ct. 832.
Id. at 45 n. 25, 96 S.Ct. 1917. Japan Whaling Association, in turn, recognized the standing of plaintiffs who claimed aesthetic injury (there, injury to their interest in whale watching) based on the government’s failure to adequately regulate a third party (there, the United States’s failure to certify that the Japanese whaling industry was exceeding its quota under international law). See 478 U.S. at 231 n. 4, 106 S.Ct. 2860.
This circuit’s case law confirms the proposition that a plaintiff satisfies the causation prong of constitutional standing by establish*441ing that the challenged agency rule permitted the activity that allegedly injured her, when that activity would allegedly have been illegal otherwise. Louisiana Energy and Power Authority (“LEPA”) v. FERC, 141 F.3d 364 (D.C.Cir.1998), for instance, involved LEPA’s challenge to a FERC decision that allowed one of LEPA’s competitors to sell electric energy at unregulated rates, thus allegedly freeing this competitor “to use predatory pricing to lure away LEPA’s customers,” id. at 366. In holding that LEPA had standing to sue, this court first noted that “ ‘petitioners sufficiently establish their constitutional standing by showing that the challenged action authorizes allegedly illegal transactions.’ ” Id. at 367 (quoting Associated Gas Distributors v. FERC, 899 F.2d 1250, 1259 (D.C.Cir.1990)). It went on to elaborate that “[a] party need not prove that the agency action it attacks is unlawful ... in order to have standing to level that attack. As we said in Claybrook v. Slater, 111 F.3d 904, 907 (D.C.Cir.1997), ‘[wjhether a plaintiff has a legally protected interest (and thus standing) does not depend on whether he can demonstrate that he will succeed on the merits.’ ” Id. at 368. Similarly, Telephone and Data Systems, Inc. v. FCC, 19 F.3d 42 (D.C.Cir.1994), recently explained that “one narrow proposition at least is clear: injurious private conduct is fairly traceable to the administrative action contested in the suit if that action authorized the conduct or established its legality,” id at 47. International Ladies’ Garment Workers’ Union v. Donovan, 722 F.2d 795 (D.C.Cir.1983), also held that the appellants had established their standing to sue because “the relief sought by appellants would make the injurious conduct of third parties complained of in this case illegal; only by taking extraordinary measures — i.e., violating the law or starting new businesses overseas—could third parties prevent redress of the appellants’ injuries,” id. at 811; see also National Wildlife Federation v. Hodel, 839 F.2d at 705 (“[Mjere indirectness of causation is no barrier to standing, and thus, an injury worked on one party by another through a third party intermediary may suffice .... It is well settled that a plaintiff has standing to challenge conduct that indirectly results in injury.... We are concerned here not with the length of the chain of causation, but on [sic], the plausibility of each of the links that comprise the chain.”) (citations and quotation marks omitted).
A question was raised at oral argument about whether Mr. Jurnove has nonetheless failed to satisfy the causation prong of constitutional standing, on the ground that the governing law simply permits the conditions that allegedly injured him, rather than requiring animal exhibitors to follow the allegedly inhumane practices. The background condition governing animal exhibitors, this argument proceeds, is that anything the exhibitors do is legal unless statutes and regulations make specific conduct illegal. Because neither the AWA nor the USDA’s implementing regulations have changed this status quo — i.e., in no way have they affected the conditions that allegedly injured Mr. Jurnove — there is no causal link between any government action and Mr. Jurnove’s injury.
This argument, however, is founded on a false premise. The proper comparison for determining causation is not between what the agency did and the status quo before the agency acted. Rather, the proper comparison is between what the agency did and what the plaintiffs allege the agency should have done under the statute. The plaintiffs’ legal theory of this case, which we accept for purposes of determining Mr. Jurnove’s standing, is grounded on their view that animal exhibitors are in fact governed by a mandatory legal regime. Specifically, the plaintiffs allege that the AWA requires the USDA to establish specific, mandatory requirements that establish humane living conditions for animals. See 7 U.S.C. § 2143(a) (1994) (directing the Secretary of Agriculture to “promulgate standards to govern the humane handling, care, treatment, and transportation of animals by dealers, research facilities, and exhibitors” and providing that these standards “shall include minimum requirements” for “a physical environment adequate to promote the psychological well-being of primates”) (emphasis added). According to this view, the AWA itself prohibits the conditions that allegedly injured Mr. Jurnove, and the *442USDA regulations misinterpret the statute by permitting these conditions. See First Amended Complaint ¶¶ 53, 57, 97, 106, 107. Both the Supreme Court and this circuit have repeatedly found causation where a challenged government action peimitted the third party conduct that allegedly caused a plaintiff injury, when that conduct would have otherwise been illegal. Neither court has ever stated that the challenged law must compel the third party to act in the allegedly injurious way. In Investment Co. Institute v. Camp, 401 U.S. 617, 91 S.Ct. 1091, 28 L.Ed.2d 367 (1971), for instance,' investment companies had standing to challenge a regulation from the Comptroller of the Currency that “authorize[dJ,” but did not require, “banks to establish and operate collective investment funds,” id. at 618-19, 91 S.Ct. 1091 (emphasis added). In Arnold Tours, Inc. v. Camp, 400 U.S. 45, 91 S.Ct. 158, 27 L.Ed.2d 179 (1970) (per curiam), independent travel agents had standing to contest “a ruling by the Comptroller that, incidental to their banking services, national banks may provide travel services for their customers,” id. at 45, 91 S.Ct. 158 (emphasis added). Barlow v. Collins, 397 U.S. 159, 90 S.Ct. 832, 25 L.Ed.2d 192 (1970), involved plaintiffs who were allegedly “suffering irreparable injury under the [challenged] regulation because it provdde[d] their landlord ‘with the opportunity to .demand that [they] and all those similarly situated assign the [upland cotton program] benefits in advance as a condition, to obtaining a lease to work the land,’” id. at 163, 90 S.Ct. 832 (emphasis added). In Association of Data Processing Service Organizations, Inc. v. Camp, 397 U.S. 150, 90 S.Ct. 827, 25 L.Ed.2d 184 (1970), data processing service organizations had standing to challenge a regulation providing that “national banks ... may make data processing services available to other banks and to bank customers,” id. at 151, 90 S.Ct. 827 (emphasis added).
In this circuit, Bristol-Myers Squibb Co. v. Shalala, 91 F.3d 1493 (D.C.Cir.1996), explicitly rejected the distinction between permissive and mandatory government regulation. There, the plaintiff challenged the legality of Food and Drug Administration (“FDA”) regulations governing the approval of new generic drugs. This court found that Bristol-Myers Squibb (“BMS”) had standing to sue, on the ground that “[i]f BMS is correct [about its claim that the FDA’s regulations violate the governing statute], then it is no answer to say that the FDA is merely permitting a competitive product to enter the market and leaving the purchasing decision to the consumer. See Telephone and Data Systems, Inc. v. FCC, 19 F.3d 42, 47 (D.C.Cir.1994) (‘injurious private conduct is fairly traceable to the administrative action contested in the suit if that action authorized the conduct or established its legality’).” Id. at 1499 (emphasis added). The dissent seeks to distinguish Bristol-Myers Squibb Co. from the present case on the ground that, in the earlier case,' the FDA had authorized the distribution of a drug under a legal regime in which no new drug could be marketed without such government approval. See Dissent at 453. In other words, Bristol-Myers Squibb Co. involved a situation in which private action that was once regulated loosely, or not at all, by the federal government, was now prohibited unless specifically permitted. The plaintiff in Bristol-Myers Squibb Co. claimed that the FDA’s exercise of its authorization authority in that instance violated its statutory mandate. See 91 F.3d at 1494-95. The dissent has provided no sound grounds for distinguishing the present case. Under the plaintiffs’ legal theory in this case, which we accept for purposes of determining their standing to sue, the AWA itself prohibits the allegedly inhumane conditions that injured Mr. Jurnove; the regulatory backdrop for the plaintiffs’ claim is that all private exhibitions that involve inhumane treatment of animals are already illegal by statute. Thus here, the plaintiffs are also contending that the USDA’s decision to permit the conditions that allegedly injured Mr.'Jurnove violated the agency’s statutory mandate.
Motor & Equipment Manufacturers Association (“MEMA") v. Nichols, 142 F.3d 449 (D.C.Cir.1998), involved a challenge to EPA regulations governing on-board emissions diagnostic devices (“OBDs”). These regulations provided that any car manufacturer who complied with California's stricter OBD *443requirements would be “ ‘deemed-to-comply’” with the federal government’s OBD requirements. Id. at 452. The manufacture of cars meeting California’s OBD standards was likely to injure the petitioners (who manufacture, rebuild, and sell spare parts) financially, but the EPA argued that its regulation had not caused this injury because the “deemed-to-comply” policy did not compel auto manufacturers to comply with California’s OBD regulations, but simply permitted them to do so. See id. at 457. This court rejected that argument, pointing out the incentives that car manufacturers have to take the “deemed-to-eomply” route, which allows them to “make one kind of each car they sell instead of two kinds, one of which would be for sale in states that follow California’s OBD regulations, and the other for sale in states that follow federal OBD regulations.” Id. We found causation, in other words, although the government regulation allowed, rather than required, the allegedly injurious third-party conduct, and we also recognized the incentives that third parties often have to minimize their expenditure of money and effort. Some animal exhibitors have similar incentives, of course, to comply with the bare requirements of the governing USDA regulations without exceeding them in any potentially expensive or time-consuming way.
Along the same lines, the plaintiffs in Telephone and Data Systems, Inc. had standing to challenge the FCC’s grant of “a conditional permit” that allowed a competitor “to construct and operate cellular communications services in the Atlantic City market,” but did not require him to do so. 19 F.3d at 44. Similarly, the plaintiffs in International Ladies’ Garment Workers’ Union had standing to challenge a Labor Department regulation that permitted the employment of people working in their homes in the knitted outerwear industry, but did not require manufacturers to employ these workers. See 722 F.2d at 799.
Mr. Jumove’s affidavit accordingly falls well within our established causation requirement for constitutional standing. He alleges that the USDA failed to adopt the specific, minimum standards that the AWA requires. He further describes how the conditions that caused him injury complied with current USDA regulations, and alleges that regulations complying with the AWA would have prohibited those conditions and protected him fi’om the injuries that his affidavit recounts.
C. Redressibility
We also find that Mr. Jurnove has satisfied the redressibility element of constitutional standing. Mr. Jurnove’s affidavit alleges that he has a current routine of regularly visiting the Game Farm and provides a finite time period within which he will make his next visit, stating that he plans to “return to the Farm in the next several weeks” and to “continue visiting the Farm to see the animals there.” Jurnove Affidavit ¶ 43. As the plaintiffs’ complaint argues, more stringent regulations, which prohibit the inhumane conditions that have consistently caused Mr. Jurnove aesthetic injury in the past, would necessarily alleviate Mr. Jurnove’s aesthetic injury during his planned, future trips to the Game Farm. See First Amended Complaint ¶¶ 53, 58. Tougher regulations would either allow Mr. Jurnove to visit a more humane Game Farm or, if the Game Farm’s owners decide to close rather than comply with higher legal standards, to possibly visit the animals he has come to know in their new homes within exhibitions that comply with the more exacting regulations.
The Supreme Court’s recent decision in FEC v. Akins, moreover, rejects the possible counterargument that the redressibility element of constitutional standing requires a plaintiff to establish that the defendant agency will actually enforce any new binding regulations against the regulated third party. There, the plaintiffs, “a group of voters with views often opposed to those of AIPAC [the American Israel Public Affairs Committee],” sought to have AIPAC classified as a “political committee” within the meaning of the Federal Election Campaign Act (“FECA”), which “imposes extensive recordkeeping and disclosure requirements upon groups that fall within the Act’s definition of a ‘political committee.’ ” 118 S.Ct. at 1781-82. The FEC argued that these plaintiffs had not estab*444lished either causation or redressibility, on the ground that, even if the Commission had accepted the plaintiffs’ interpretation of FECA, “it is possible that ... [the FEC] would still have decided in the exercise of its discretion not to require AIPAC to produce the information.” Id. at 1786. The Supreme Court soundly rejected this argument, noting:
that fact does not destroy Article III ‘causation’ [or redressibility,] for we cannot know that the FEC would have exercised its prosecutorial discretion in this way. Agencies often have discretion about whether or not to take a particular action. Yet those adversely affected by a discretionary agency decision generally have standing to complain that the agency based its decision upon an improper legal ground. If a reviewing court agrees that the agency misinterpreted the law, it will set aside the agency’s action and remand the case — even though the agency (like a new jury after a mistrial) might later, in the exercise of its lawful discretion, reach the same result for a different reason.
Id. (citations omitted).
Mr. Jurnove, accordingly, has met all three of the constitutional requirements for standing.
D. Prudential Standing/Zone of Interests
Mr. Jurnove also falls within the zone of interests protected under the AWA’s provisions on animal exhibitions. As the Supreme Court has recently reaffirmed, the zone of interests test is generous and relatively undemanding. “[T]here need be no indication of congressional purpose to benefit the would-be plaintiff.” National Credit Union Admin. v. First National Bank & Trust Co., — U.S. -,-, 118 S.Ct. 927, 934, 140 L.Ed.2d 1 (1998) (citation and quotation marks omitted). Instead, the test, a gloss on APA § 10(a), 5 U.S.C. § 702 (1994), asks only “whether the interest sought to be protected by the complainant is arguably within the zone of interests to be protected by the statute,” National Credit Union Admin., 118 S.Ct. at 935 (citation, internal quotation marks, and alteration omitted); see also Akins, 118 S.Ct. at 1783 (“[Prudential standing is satisfied when the injury asserted by a plaintiff arguably falls within the zone of interests to be protected or regulated by the statute in question.”) (citation, internal quotation marks, and alterations omitted). Our circuit has further explained that “[t]his analysis focuses, not on those who Congress intended to benefit, but on those who in practice can be expected to police the interests that the statute protects.” Mova Pharmaceutical Corp. v. Shalala, 140 F.3d 1060, 1075 (D.C.Cir.1998); see also ALDF I, 23 F.3d at 502 (“The [zone of interests] test precludes review of administrative action if the particular interest asserted is ‘so marginally related to or inconsistent with the purposes implicit in the statute that it cannot reasonably be assumed that Congress intended to permit the suit.’ ”) (quoting Clarke v. Securities Indus. Ass’n, 479 U.S. 388, 399, 107 S.Ct. 750, 93 L.Ed.2d 757 (1987)); Autolog Corp. v. Regan, 731 F.2d 25, 29-30 (D.C.Cir.1984) (“[T]he zone of interests test requires some indicia — however slight — that the litigant before the court was intended to be protected, benefitted or regulated by the statute under which suit is brought. Courts should give broad compass to a statute’s zone of interests in recognition that this test was originally intended to expand the number of litigants able to assert their rights in court.”) (citations and internal quotation marks omitted).
In this case, logic, legislative history, and the structure of the AWA, all indicate that Mr. Jurnove’s injury satisfies the zone of interests test. The very purpose of animal exhibitions is, necessarily, to entertain and educate people; exhibitions make no sense unless one takes the interests of their human visitors into account. The legislative history of both the 1985 amendments to the Animal Welfare Act and the 1970 act that first included animal exhibitions within the AWA confirms that Congress acted with the public’s interests in mind.
In introducing the 1985 amendments, Senator Robert Dole explained “that we need to ensure the public that adequate safeguards are in place to prevent unnecessary abuses to animals, and that everything possible is being done to decrease the pain of animals during experimentation and testing.” 131 *445Cong. Rec. 29,155 (1985) (statement of Sen. Dole) (emphasis added). The Congressmen who went on the House floor to introduce the act that first extended the AWA to cover animal exhibitions recognized that their bill “ha[d] been',a focal point of concern among animal lovers throughout the Nation for some time” and spoke of the “great pleasure” that animals bring to the people who see them. 116 Cong. Rec. 40,159 (1970) (statement of Rep. Mizell); see also H.R. Rep. No. 91-1651, at 1 (1970) (“Beginning with the legislation passed in 1966 (Public Law 89-544), the United States Government has implemented a statutory mandate that small helpless creatures deserve the care and protection of a strong and enlightened public.’’) (emphasis added). Indeed, Congress had placed animal exhibitions within the scope of the AWA after hearings documenting how inhumane conditions at these exhibitions affected the people who came and watched the animals there. See Care of Animals Used for Research, Experimentation, Exhibition, or Held for Sale as Pets: Hearings on H.R. 13957 Before the Subcomm. on Livestock and Grains of the House Comm, on Agriculture, 91st Cong. 38 (1970) (letter from John M. Mehrtens) [hereinafter Hearings]; id. at 39 (letter from Chris Sullivan); id. at 67 (statement of Pearl Twyne); id. at 79 (statement of Mary Frances Morrisette).
Throughout, the Congressmen responsible for including animal exhibitions within the AWA encouraged the continued monitoring of humane societies and their members. They spoke, for instance, of how America had long depended on humane societies to bring the mistreatment of animals to light. See, e.g., 116 Cong. Rec. 40,305 (1970) (statement of Rep. Whitehurst). The Congressmen further acknowledged that humane societies were the moving force behind the legislation to include animal exhibitions within the AWA. See, e.g., 116 Cong. Rec. 40,156 (1970) (statement of Rep. Foley).
The structure of the AWA also makes clear that Mr. Jurnove falls within the statute’s zone of interests. While the AWA establishes oversight committees with private citizen members for research facilities, see 7 U.S.C. § 2143(b)(1) (1994), it created no counterpart for animal exhibitions. But, as the legislative history shows, the AWA anticipated the continued monitoring of concerned animal lovers to ensure that the purposes of the Act were honored. Mr. Jurnove, a regular viewer of animal exhibitions regulated under the AWA, clearly falls within the zone of interests the statute protects. His interests are among-those that Congress sought to benefit through the AWA, and he certainly is one of the individuals “who in practice can be expected to police the interests that the statute protects.” Mova Pharmaceutical Corp., 140 F.3d at 1075.
III. Conclusion
Mr. Jurnove has standing to sue. He satisfies the injury, causation, and redressibility elements of constitutional standing, and also falls within the zone of interests for the Animal Welfare Act. We accordingly have no need to consider the standing of the other individual plaintiffs. We leave a determination of the merits of the plaintiffs’ claim to a future panel of this court.
So ordered.
. Audrey Rahn, a fourth individual plaintiff, also appeared before the district court in this case. However, Rahn's claim focused only on the USDA’s allegedly inadequate enforcement of its existing regulations, an issue not before this court on appeal. See Animal Legal Defense Fund, Inc. v. Glickman, 943 F.Supp. 44, 51, 62-64 (D.D.C.1996).
. The Animal Legal Defense Fund ("ALDF”), an animal welfare organization, alleges that the USDA violated the notice and comment provisions of the Administrative Procedure Act ("APA"), 5 U.S.C. § 553 (1994), by failing to provide adequate opportunity to comment on the agency’s decision to require regulated entities to keep their plans at their own facilities, see 9 C.F.R. § 3.81(e)(3), thereby protecting these plans from disclosure under the Freedom of In*429formation Act, 5 U.S.C. § 552 (1994). The panel opinion held that ALDF lacked standing to sue. and the in banc court limited itself to considering Marc Jurnove's standing.
. Although the crux of the plaintiffs’ complaint alleges that the USDA failed to promulgate minimum standards as required by the AWA, the complaint also states that the USDA has inadequately enforced even its existing regulations, by allegedly failing to inspect facilities and by allegedly instructing its inspectors to avoid documenting violations. See First Amended Complaint ¶¶ 122-23. As the district court found, see 943 F.Supp. at 62-64, the USDA’s decisions about whether to undertake enforcement actions are generally unsuitable for judicial review, see, e.g., Heckler v. Chaney, 470 U.S. 821, 831, 105 S.Ct. 1649, 84 L.Ed.2d 714 (1985). The plaintiffs have not appealed that judgment to this court.
. The district court also held that ALDF had standing to sue in its owii capacity on its notice and comment claim, see 943 F.Supp. at 53-54, and found for ALDF on the merits, see id. at 61-62.
. The dissent attempts to limit Animal Welfare Institute to support standing only where the challenged governmental action is "diminishing the opportunity to observe [the animal], not affecting the quality of the observation.” Dissent at 448. This statement does not accurately reflect either the injury alleged in Animal Welfare Institute or this court’s holding in that case. In articulating the nature of their aesthetic injury, the Animal Welfare Institute plaintiffs alleged an interest in observing Cape fur seals who lived under "not ... inhumane" conditions, 561 F.2d at 1007—in other words, an interest in the quality of animal life, rather than the quantity of animals alive. To be sure, the "inhumane treatment” that concerned these particular plaintiffs revolved, as the dissent notes, around the manner in which the seals were being killed. See id. at 1012-13. But this fact does not reduce the plaintiffs' claim to one challenging the government only for causing the diminishment of an animal population. To the contrary, the plaintiffs in Animal Welfare Institute were alleging aesthetic injury based on how the Cape fur seals were living and how they were dying; the plaintiffs did not simply focus on the fact that the seals were, in fact, dying. Moreover, in holding that the plaintiffs' aesthetic interests would satisfy the requirements of standing if the plaintiffs could establish that they were among the injured, this court never distinguished between the plaintiffs' claims based on the quality of animal life and those based on the number of animals in existence.
. Not surprisingly, the dissent also' reads Humane Society v. Hodel to support standing only where the challenged governmental action has or will deplete the supply of an animal population. See Dissent at 448. In fact, the case explicitly rejects that reading. The complaint in Humane Society v. Hodel stated both "that the existence of hunting on wildlife refuges forces Society members to witness animal corpses and environmental degradation” (a claim based on the quality of the aesthetic experience of observing animals) and that the challenged hunting regulations also "deplet[ed] the supply of animals and birds that refuge visitors seek to view” (a claim based on the number of animals in existence). 840 F.2d at 42. This court, moreover, clearly recognized both of these claims, stating: “These are classic aesthetic interests, which have always enjoyed protection under standing analysis.” Id. (emphasis added).
. It was suggested, not altogether facetiously, at oral argument that recognition of an aesthetic interest in observing animals might be problematic because it could encapsulate the aesthetic interest of a sadist in seeing animals living under ¿«humane conditions and the injury he suffered upon seeing particular animals living in a humane environment. There is a major difficulty with this argument. The meaning of "injury in fact” under our constitutional standing test does not incorporate every conceivable aesthetic interest. To the contrary, our standing jurisprudence defines injury in fact as "an invasion of a legally protected interest." Defenders of Wildlife, 504 U.S. at 560, 112 S.Ct. 2130 (emphasis added). Thus, if the hypothetical sadist challenged the regulations at issue here (presumably, for being too protective of animal welfare), he would not be able to establish injury in fact because the AWA, the relevant statute, recognizes no interest in sadism. To the contrary, it requires dealers, exhibitors, and research facilities to treat animals humanely. See 7 U.S.C. § 2143. This sadist would also find his claim immediately excluded under the APA, which only grants standing to people "adversely affected or aggrieved by agency action within the meaning of a relevant statute." 5 U.S.C. § 702 (1994) (emphasis added); see also Clarke v. Securities Indus. Ass’n, 479 U.S. 388, 394, 107 S.Ct. 750, 93 L.Ed.2d 757 (1987); Association of Data Processing Serv. Orgs., Inc. v. Camp, 397 U.S. 150, 153-54, 90 S.Ct. 827, 25 L.Ed.2d 184 (1970); ALDF II, 29 F.3d at 723; ALDF I, 23 F.3d at 499.
The dissent ‘ attempts further to build on the suggestion put forth at oral argument that no one should be able to establish constitutional standing based on an aesthetic interest in observing animals living under humane conditions because definitions of what is "humane” may differ so widely. See Dissent at 448-49. But the dissent, again, forgets that not every aesthetic interest can form the basis for a lawsuit; our injury-in-fact test protects only those aesthetic interests that have been "legally protected.” 504 U.S. at 560, 112 S.Ct. 2130. At its héart, the dissent’s complaint may reflect a fear that the AWA does not do enough to define what it means by "humane,” aldiough the statute does indicate, in its sections focusing on animal research, a particular concern with minimizing "animal pain and distress.” See, e.g., 7 U.S.C. § 2143(a)(3)(A). Yet "humane” does convey a basic meaning of compassion, sympathy, and consideration for animals’ health, safety, and well-being, and it is not that unusual for this court to apply relatively broad statutory language to particular claims by looking to the normal usage of words, even when different people may disagree as to their application to a variety of factual situations.
. The Mineral King Valley "is designated as a national game refuge by special Act of Congress." 405 U.S. at 728, 92 S.Ct. 1361. The Sierra Club alleged, inter alia, "that various aspects of the proposed development contravene federal laws and regulations governing the preservation of ... game refuges.” Id. at 730, 92 S.Ct. 1361.
. The United States argues that Mr. Jurnove has not demonstrated causation, on the ground that the above-described injuries are self-inflicted. The assertion appears to turn on the fact that Mr. Jurnove first traveled to the Game Farm "in [his] capacity as an equine investigator, [after being] apprised that several ponies needed to be checked on at that location.” Jurnove Affidavit ¶ 7. This argument may — or may not — have merit with regard to equine mistreatment at the Game Farm. However, there is no need in this case to offer any opinion about whether so-called "self-inflicted" wounds can give rise to standing. According to Mr. Jurnove's uncontested affidavit, he visited the primates at the Game Farm, the subject of the present suit, out of an aesthetic interest in observing animals living under humane conditions. See id. ("Once [Mr. Jurnove] was there [at the Game Farm],” he decided "to look around at the other animals housed there” "in furtherance of [his] appreciation for exotic animals and [his] desire to observe and enjoy them.”).
. The dissent makes-much of the fact that Mr. Jurnove occasionally expresses doubt in his affidavit about the soundness of the USDA's multiple determinations that the Game Farm was in compliance with essentially all of the relevant regulations, contending that "the thrust of the affidavit” is that "the USDA went through the motions and wrote up incorrect reports.” Dissent at 451. This argument is flawed on two counts. First, Mr. Jurnove's affidavit is the wrong place to look for a statement of the plaintiffs' legal theory of this case. Mr. Jurnove is not a lawyer and his affidavit purports to articulate only his alleged injuries. The plaintiffs' legal arguments are put forth in their complaint, where they explicitly allege that the conditions at the Game Farm that caused Mr. Jurnove injury complied with the present USDA regulations. See First Amended Complaint HV 53, 58. Second, even if we were to look to Mr. Jurnove's affidavit to determine the plaintiffs' legal theory, the "thrust of the affidavit" is certainly not that the conditions at the Game Farm violated the USDA’s regulations. Indeed, so far as the record before us reflects, no decisionmaking authority has ever made the determination that there are widespread regulatory violations at the Game Farm. And the USDA, the agency with regulatory control over the Game Farm, repeatedly came to the opposite conclusion, finding that the Game Farm was in legal compliance with the USDA regulations that the plaintiffs challenge here.