Full opinion text
Opinion by Judge BYBEE; Dissent by Judge KLEINFELD BYBEE, Circuit Judge: Daniel Guggenheim and others bring a facial challenge to the City of Goleta’s mobile home rent control ordinance. Guggenheim argues that the ordinance, which effects a transfer of nearly 90 percent of the property value from mobile home park owners to mobile home tenants, constitutes a regulatory taking under Penn Central Transportation Co. v. New York City, 438 U.S. 104, 98 S.Ct. 2646, 57 L.Ed.2d 631 (1978). We have fielded such challenges before, but have never reached the merits of the takings claim. See, e.g., Equity Lifestyle Props., Inc. v. County of San Luis Obispo (“Equity Lifestyle ”), 548 F.3d 1184, 1190 n. 11 (9th Cir.2008); Carson Harbor Vill. Ltd., v. City of Carson, 37 F.3d 468, 475-77 (9th Cir.1994), overruled on other grounds by WMX Techs., Inc. v. Miller, 104 F.3d 1133, 1136 (9th Cir.1997) (en banc); Levald, Inc. v. City of Palm Desert, 998 F.2d 680, 686-89 (9th Cir.1993); Sierra Lake Reserve v. City of Rocklin, 938 F.2d 951, 955 (9th Cir.1991), vacated, 506 U.S. 802, 113 S.Ct. 31, 121 L.Ed.2d 4 (1992). To determine whether a taking has occurred we must decide several issues. We must first determine whether the mobile home park owners have standing to bring this case. Additionally, we must consider whether this case is ripe under Williamson County Regional Planning Commission v. Hamilton Bank of Johnson City, 473 U.S. 172, 105 S.Ct. 3108, 87 L.Ed.2d 126 (1985). If so, then we must determine whether the city ordinance constitutes a regulatory taking under Penn Central. We also address challenges to the ordinance under the Due Process and Equal Protection Clauses. The district court did not address either the standing or ripeness questions due to the unusual procedural history of the case, but implicitly found the case was properly brought. The district court found that no taking had occurred. For the reasons explained below, we agree with the district court that this case is properly brought and ripe for decision, but we disagree with the district court on the merits of the takings claim. Because we find that a taking has occurred, we reverse and remand to the district court to determine what compensation is due. We affirm the district court’s judgment on the due process and equal protection claims. I A The Takings Clause of the Fifth Amendment, made applicable to the states through the Fourteenth Amendment, see Chicago, B. & Q.R. Co. v. Chicago, 166 U.S. 226, 236, 17 S.Ct. 581, 41 L.Ed. 979 (1897), provides that “private property [shall not] be taken for public use, without just compensation.” The Takings Clause “does not prohibit the taking of private property, but instead places a condition on the exercise of that power.” First English Evangelical Lutheran Church of Glendale v. County of Los Angeles, 482 U.S. 304, 314, 107 S.Ct. 2378, 96 L.Ed.2d 250 (1987). The Takings Clause was drafted so as “not to limit the governmental interference with property rights per se, but rather to secure compensation in the event of otherwise proper interference amounting to a taking.” Id. at 315, 107 S.Ct. 2378. The Takings Clause “ ‘bar[s] Government from forcing some people alone to bear public burdens which, in all fairness and justice, should be borne by the public as a whole.’ ” Lingle v. Chevron U.S.A. Inc., 544 U.S. 528, 537, 125 S.Ct. 2074, 161 L.Ed.2d 876 (2005) (quoting Armstrong v. United States, 364 U.S. 40, 49, 80 S.Ct. 1563, 4 L.Ed.2d 1554 (1960)). To determine whether a mobile-home rent control ordinance constitutes a taking under the Constitution, we must first understand some unique characteristics of mobile homes. “The fact that these homes can be moved does not mean that they do move.” John Steinbeck, Travels With Charley: In Search of America 96 (Penguin Books 1986) (1962). As described by the Supreme Court: The term “mobile home” is somewhat misleading. Mobile homes are largely immobile as a practical matter, because the cost of moving one is often a significant fraction of the value of the mobile home itself. They are generally placed permanently in parks; once in place, only about 1 in every 100 mobile homes is ever moved.... A mobile home owner typically rents a plot of land, called a “pad,” from the owner of a mobile home park. The park owner provides private roads within the park, common facilities such as washing machines or a swimming pool, and often utilities. The mobile home owner often invests in site-specific improvements such as a driveway, steps, walkways, porches, or landscaping. When the mobile home owner wishes to move, the mobile home is usually sold in place, and the purchaser continues to rent the pad on which the mobile home is located. Yee v. City of Escondido, 503 U.S. 519, 523, 112 S.Ct. 1522, 118 L.Ed.2d 153 (1992) (citation omitted). The County of Santa Barbara, California (the “County”), first enacted its Rent Control Ordinance (the “RCO”) in 1979, and amended it in 1987. In 2002, the City of Goleta incorporated within the County. As required by California law, the new City of Goleta immediately adopted by reference the County’s code in its entirety, including the RCO, as its provisional new code. See Cal. Gov’t Code § 57376 (2008); City of Goleta Ordinance No. 02-01. About two months later, the City readopted by reference most provisions of the County code, including the RCO, as permanent city ordinances. City of Goleta Ordinance No. 02-17. The statement of “Purpose” in the RCO has remained unchanged since the RCO was first passed by the County in 1979. The purpose was to prevent mobile home park owners from charging exorbitant rents to exploit local housing shortages and the fact that mobile home owners could not easily move their homes: A growing shortage of housing units resulting in a critically low vacancy rate and rapidly rising and exorbitant rents exploiting this shortage constitutes serious housing problems affecting a substantial portion of those Santa Barbara County residents who reside in rental housing.... Especially acute is the problem of low vacancy rates and rapidly rising and exorbitant rents in mobile home parks in the County of Santa Barbara. Because of such factors and the high cost of moving mobilehomes, ... the board of supervisors finds and declares it necessary to protect the owners and occupiers of mobilehomes from unreasonable rents while at the same time recognizing the need for mobile home park owners to receive a fair return on their investment and rent increases sufficient to cover their increased costs. RCO § 11A-1. The RCO limits any increases in mobile home rents on an annual basis to 75 percent of the increase in the local Consumer Price Index (“CPI”). RCO §§ 11A-5(a)(2), llA-5(a)(3), HA-5(g). This increase is referred to as the “automatic increase.” Mobile home park owners may also increase the rent by an additional amount to pass through increased operating costs, capital expenses, and capital improvements. This increase is referred to as the “discretionary increase.” RCO § HA-5(f)(l); 11A-6. The RCO sets out an arbitration process by which park owners must work with the mobile home owners and an arbitrator to determine the total amount of the permissible rent increase for each year. RCO §§ 11A-4, 11A-5. The arbitrator must follow a complicated formula to determine the amount of any increase in excess of the automatic increase: (1) First, grant one-half of the automatic increase to management as a just and reasonable return on investment. The arbitrator shall have no discretion to award additional amounts as a just and reasonable return on investment. (2) Next, grant one-half of the automatic increase to management to cover increased operating costs. The arbitrator shall have no discretion to award less than this amount for operating costs. (3) Next, add an amount to cover operating costs, if any, in excess of one-half of the automatic increase. The arbitrator shall have discretion to add such amounts as are justified by the evidence and otherwise permitted by this chapter. (4) Next, add an amount to cover new capital expenses. Where one-half of the automatic increase is more than the actual increase in operating costs for the year then ending, the arbitrator shall offset the difference against any increases for new capital expenses. (5) Next, add an amount to cover old capital expenses. Where one-half of the automatic increase is more than the actual increase in operating costs for the year then ending, the arbitrator shall offset the difference against any increase for old capital expenses unless such difference has already been used to offset an increase for a new capital expense or another old capital expense .... (6) Finally, add an amount to cover increased costs for capital improvements, if any. The arbitrator shall have discretion to add such amount as is justified by the evidence and otherwise permitted by this ordinance. RCO § 11A-5(I). The RCO also contains a vacancy control provision, which limits the permissible rent increase to 10 percent when a unit is sold. RCO § 11A-14. In sum, the RCO mandates that a “just and reasonable return” for the park owners must always be less than or equal to exactly one half of 75 percent of the annual increase of the CPI. The RCO permits park owners to go to arbitration to pass through additional costs, but such costs must be re-captured without any return on investment. In the event a tenant sells his or her unit, the park owners are entitled to a one-time rent increase of 10 percent; subsequent increases are capped by the regular formula. B 1 Appellants Daniel Guggenheim, Susan Guggenheim, and Maureen H. Pierce (collectively, the “Park Owners”) purchased the Ranch Mobile Estates mobile home park (“the Park”) in 1997, at which time the Park was located in an unincorporated part of the County. At the time of the purchase, therefore, the Park was subject to the County’s RCO as amended in 1987. When the City incorporated in 2002, the Park fell within the new city’s jurisdiction. Because the City adopted the RCO by reference, the Park continued to be subject to the RCO after the City incorporated. A month after the City incorporated, the Park Owners brought suit in federal court, alleging only facial challenges to the RCO. The Park Owners claimed, inter alia, violations of the Takings Clause, the Due Process Clause, and the Equal Protection Clause. The Park Owners also raised complex state law claims, claiming the City failed to follow proper procedures required by the California Government Code when it enacted the RCO. Apparently, the Park Owners initiated the lawsuit in 2002, even though they purchased the Park in 1997, because they claimed the City adopted the RCO without any “hearings or studies or investigations as to whether the County’s Ordinance was needed or appropriate for the City.” The Park Owners’ complaint represented that they “had attempted to meet with the City officials-elect to discuss the City’s potential adoption of’ the County’s RCO, and had “applied to the City for relief from the potential vacancy control restriction in the County Ordinance^] but it was nevertheless adopted without any change by Defendant City.” The Park Owners complained that when it adopted the RCO, “[t]he City failed to review the County Code or make any findings on whether there was a purpose or need” for the RCO in the current real estate market. The district court stayed the viable federal claims under the Pullman doctrine, to permit the resolution of certain complex state law claims that might “moot or narrow the constitutional questions.” San Remo Hotel v. City and County of San Francisco, 145 F.3d 1095, 1104 (9th Cir.1998). The parties settled their state law claims after litigating in Santa Barbara Superior Court, and then returned to federal court for a second time. 2 Back in federal court, the Park Owners moved for partial summary judgment. The district court reviewed the undisputed facts and the affidavits and documents proffered by the parties. The court found that during the time the Park Owners owned the Park, housing costs in the City increased approximately 225 percent. Because of the RCO, the rents charged by the Park Owners did not keep pace with this increase. The below-market rents resulted in the ability of mobile home owners to sell their homes at a significant premium (the transfer premium). The district court found, based on a report provided by the Park Owners, that the transfer premium amounted to, on average, 88 percent of the sale price. “In other words,” the district court found, “an average mobile home worth $12,000 would sell for approximately $100,000.” The district court found that “the uncontroverted facts ... establish the existence of a premium,” and that even “[t]he City has acknowledged the existence of such a premium.” The district court granted summary judgment on the takings claim in favor of the Park Owners on October 29, 2004. At the time the district court made its determination, the law in the Ninth Circuit was that a government regulation effected a taking if such regulation did not “substantially advance” legitimate state interests. See, e.g., Agins v. City of Tiburon, 447 U.S. 255, 260, 100 S.Ct. 2138, 65 L.Ed.2d 106 (1980); Richardson v. City and County of Honolulu, 124 F.3d 1150, 1165-66 (9th Cir.1997) (holding that a condominium rent control ordinance that permits incumbent condominium owners to capitalize the net present value of reduced land rent will not substantially further its goal of creating affordable owner-occupied housing and thus constitutes a taking). The district court found it undisputed that the RCO effected a one-time wealth transfer from the Park Owners to the incumbent tenants, and that the RCO failed to substantially advance its stated purpose of providing affordable housing. The court found, therefore, that the RCO was an unconstitutional regulatory taking and the Park Owners were entitled to just compensation. The City timely appealed. On May 23, 2005, while the case was on appeal, the Supreme Court decided Lingle v. Chevron U.S.A. Inc., 544 U.S. 528, 125 S.Ct. 2074, 161 L.Ed.2d 876 (2005). Lingle repudiated the “substantially advances” theory upon which the Park Owners had prevailed. In light of this development, the parties stipulated to vacate the district court’s judgment and return for what would now be their fourth round of litigation before a trial court. 3 After some renewed pre-trial litigation, the district court issued a series of summary judgment rulings in which it found in favor of the City on each of the Park Owners’ remaining constitutional claims. On April 5, 2006, the district court denied the Park Owners’ motion for partial summary judgment, finding that the Park Owners were not entitled to judgment as a matter of law as to whether the RCO constituted a regulatory taking under Penn Central Transportation Co. v. New York City, 438 U.S. 104, 98 S.Ct. 2646, 57 L.Ed.2d 631 (1978). The court reviewed both parties’ expert reports and found that the evidence as to the economic impact of the regulation was “mixed”: Although [the Park Owners] have enjoyed a rate of return comparable to other real estate investments, [the Park Owners’] evidence tends to suggest that they would have earned more — perhaps much more — in the absence of the RCO. The district court also denied the Park Owners’ motion for summary judgment on their substantive due process and equal protection claims. The parties continued to prepare for trial — designating experts, agreeing to witness and exhibit lists, and filing motions in limine. On July 27, 2006, the district court sua sponte issued an Order to Show Cause why the court should not, on its own motion, enter summary judgment in favor of the City. On September 6, 2006, after reviewing the parties’ responses, the district court entered summary judgment in favor of the City on all of the Park Owners’ remaining causes of action. The court stated: Because this is a facial challenge to the ordinance in question, the evidence [the Park Owners] seek to present at trial vis[-]a[-]vis their Fifth Amendment [T]akings [C]lause claim is irrelevant. To facially attack the ordinance as an uncompensated “taking,” [the Park Owners] must demonstrate that the mere enactment of the ordinance constitutes a taking. The court then complained that the Park Owners had “impermissibly attempted to convert this action, de facto, into an as-applied challenge.” The district court did not, however, identify which evidence it found “irrelevant” or “impermissible” in a facial takings claim. The district court also did not make explicit whether it incorporated its April 5 analysis of the Park Owners’ Penn Central claim into its final judgment or whether it entered final judgment solely on the ground the Park Owners were barred from presenting evidence in a facial challenge. The Park Owners appealed in a timely manner. II This case has already been litigated through three full rounds at the trial level, including one in state court and two in federal court, producing one victory for the Park Owners, one for the City, and one tie (the settlement). Accordingly, it may come as a surprise that before we reach the merits of the Park Owners’ appeal, we must consider whether the plaintiffs have standing to bring this case and whether this case is ripe for decision. A Under Article III, our power to adjudicate is limited to “cases” and “controversies.” U.S. Const, art. Ill, § 2, cl. 1. Accordingly, we are not authorized to decide a dispute “merely because a party requests a court of the United States to declare its legal rights, and has couched that request for forms of relief historically associated with courts of law in terms that have a familiar ring to those trained in the legal process.” Valley Forge Christian Coll. v. Ams. United for Separation of Church and State, Inc., 454 U.S. 464, 471, 102 S.Ct. 752, 70 L.Ed.2d 700 (1982). Rather, we must first determine whether a litigant has “standing” to bring suit in the federal forum for his alleged injury. See id. at 471-72, 102 S.Ct. 752. The Supreme Court has defined standing generally as “the question of ... whether the litigant is entitled to have the court decide the merits of the dispute or of particular issues.” Warth v. Seldin, 422 U.S. 490, 498, 95 S.Ct. 2197, 45 L.Ed.2d 843 (1975). We have recognized that a plaintiff must at minimum present a suit with “three elements” in order to satisfy us that this question can be answered affirmatively. Colwell v. Dep’t of Health & Human Servs., 558 F.3d 1112, 1121-22 (9th Cir.2009) (quoting Lujan v. Defenders of Wildlife, 504 U.S. 555, 560, 112 S.Ct. 2130, 119 L.Ed.2d 351 (1992)). A plaintiff must first “have suffered an injury in fact — an invasion of a legally protected interest which is (a) concrete and particularized and (b) actual or imminent, not conjectural or hypothetical.” Lujan, 504 U.S. at 560, 112 S.Ct. 2130 (internal quotations omitted). “Second, there must be a causal connection between the injury and the conduct complained of — the injury has to be fairly traceable to the challenged action of the defendant, and not the result of the independent action of some third party not before the court.” Id. (internal quotation marks and alterations omitted). Finally, “it must be ‘likely,’ as opposed to merely ‘speculative,’ that the injury will be ‘redressed by a favorable decision.’ ” Id. at 561, 112 S.Ct. 2130. There is no question that the latter two elements of the standing inquiry are satisfied by the Park Owners. The Park Owners submitted a comprehensive analysis of the effects of the RCO which demonstrated that the RCO reduced the rents the Park Owners could collect by approximately $10,000 per year. See infra n. 14. The link between the Park Owners’ injury and the RCO is thus not “tenuous” but “fairly traceable” to the City’s action. See Tyler v. Cuomo, 236 F.3d 1124, 1132-33 (9th Cir.2000). If we were to determine that the RCO effected a taking, the Park Owners are due compensation for their loss— thus, it is not “merely speculative ... that the injury will be redressed by a favorable decision.” Id. at 1133. Nevertheless, we must still determine whether the Park Owners have an “actual injury” — that they have “alleged such a personal stake in the outcome of the controversy as to assure that concrete adverseness which sharpens the presentation of issues upon which the court so largely depends for illumination of difficult constitutional questions.” Baker v. Carr, 369 U.S. 186, 204, 82 S.Ct. 691, 7 L.Ed.2d 663 (1962). This “actual injury” requirement “tends to assure that the legal questions presented to the court will be resolved, not in the rarified atmosphere of a debating society, but in a concrete factual context conducive to a realistic appreciation of the consequences of judicial action.” Valley Forge, 454 U.S. at 472, 102 S.Ct. 752. Although in this case there is every indication that the Park Owners (and the City, who never raised the question of standing) believed they had a personal stake in the outcome of the controversy— indeed, both parties litigated the merits of the claim several times over — we have previously denied standing to similar plaintiffs bringing facial takings challenges against rent control ordinances. See Equity Lifestyle, 548 F.3d at 1193; Carson Harbor Village, 37 F.3d at 475-76. In Carson Harbor Village, we held that a mobile home park owner who had purchased the regulated property after the allegedly unconstitutional ordinance was passed did not have standing to state a facial takings claim. 37 F.3d at 476. We reasoned that the park owner’s claims “necessarily rest on the premise that an interest in property was taken from all mobile home property owners upon the statute’s enactment.” Id. Accordingly, because “[i]n a facial taking, the harm is singular and discrete, occurring only at the time the statute is enacted.... [b]ecause [the plaintiff] did not own the property when the statutes were enacted and when the alleged facial takings occurred, it has incurred no injury entitling it to assert a facial claim.” Id. Likewise, in Equity Lifestyle, we dismissed a mobile home park owner’s facial takings claim because “the injury is treated as having occurred to the previous landowner” who occupied the property at the moment the allegedly offending statute was enacted. 548 F.3d at 1193. We have also noted, without deciding the issue, that the Supreme Court’s opinion in Palazzolo v. Rhode Island, 533 U.S. 606, 121 S.Ct. 2448, 150 L.Ed.2d 592 (2001), calls into question the principle that a subsequent property owner does not have standing to assert a facial challenge to a statutory enactment thought to effectuate a taking. See Equity Lifestyle, 548 F.3d at 1190 n. 11, 1193 n. 15. In Palazzolo, the Court rejected the notion that only the landowner at the time of the statute’s enactment could assert a valid takings claim under Penn Central. See 533 U.S. at 630, 121 S.Ct. 2448 (“[A takings claim] is not barred by the mere fact that title was acquired after the effective date of the state-imposed restriction.”). The Court remarked that “[a] law does not become a background principal for subsequent owners by enactment itself.” Id; see Equity Lifestyle, 548 F.3d at 1190 n. 11. These statements, as we have previously noted, cast doubt on Carson Harbor Village’s rationale for denying standing to subsequent purchasers — they indicate that a subsequent purchaser may have a stake in a facial suit against the regulation. See id. In this case, however, even if the rule of Carson Harbor Village survives Palazzolo, the Park Owners satisfy Article Ill’s case or controversy requirements. Although the Park Owners purchased the burdened property in 1997, eighteen years after the County first passed the RCO and ten years after it was amended, the City adopted the RCO in 2002, after the Park Owners were in possession of the Park. Additionally, the parties stipulated that there was some time period between the City’s incorporation and the City’s adoption of the RCO in which no rent control ordinance was in effect. See supra n. 2. Thus, assuming that Carson Harbor Village is still good law, even though the Park Owners might not have standing to challenge the County’s use of the RCO, they are precisely the sort of plaintiffs Carson Harbor Village envisioned bringing a facial challenge to the City’s RCO. See Carson Harbor Village, 37 F.3d at 476 (“[Fjacial [takings] claims necessarily rest on the premise that an interest in property was taken from all mobile home property owners upon the statute’s enactment.”). We therefore find that the Park Owners have standing to bring their takings claim. B “[A] takings claim must[also] ... comply with timeliness requirements. It must be filed neither too early (unripe) nor too late (barred by a statute of limitations).” Equity Lifestyle, 548 F.3d at 1190. In Williamson County Regional Planning Commission v. Hamilton Bank of Johnson City, 473 U.S. 172, 185, 105 S.Ct. 3108, 87 L.Ed.2d 126 (1985), the Supreme Court held that a takings claim is not ripe until the property owner has attempted to obtain just compensation for the loss of his or her property through the procedures provided by the state for obtaining such compensation and been denied. Id. at 195, 105 S.Ct. 3108. Williamson also set forth an additional hurdle, applicable only to as-applied challenges: the property owner must have received a “final decision” from the appropriate regulatory entity as to how the challenged law will be applied to the property at issue. Id. at 192-93, 105 S.Ct. 3108. The latter requirement is not applicable here because the Park Owners have raised only a facial challenge. “Facial challenges are exempt from the [“final decision”] prong of the Williamson ripeness analysis because a facial challenge by its nature does not involve a decision applying the statute or regulation.” Hacienda Valley Mobile Estates v. City of Morgan Hill, 353 F.3d 651, 655 (9th Cir.2003) (citation omitted). The district court found that this case was ripe, although on a slightly different theory. When the Park Owners filed suit in federal district court, they had approached the City of Goleta to ask for relief from the RCO, but had not brought an inverse condemnation suit in a California court. Thus, the Park Owners had failed to satisfy Williamson’s first prong, that the property owners exhaust state remedies. The district court found that the Park Owners’ facial challenges were ripe nevertheless because of a narrow exception to the Williamson requirement. At the time the Park Owners brought this suit, a claim that a law constituted a taking because it did not “substantially advance” the purpose of that law was exempt from the Williamson requirement. See Yee, 503 U.S. at 533-34, 112 S.Ct. 1522. The Court had created the exception for challenges on the “substantially advances” theory because “this allegation does not depend on the extent to which petitioners are deprived of the economic use of their particular pieces of property or the extent to which these particular petitioners are compensated.” Id. at 534, 112 S.Ct. 1522 (citing Keystone Bituminous Coal Ass’n v. DeBenedictis, 480 U.S. 470, 495, 107 S.Ct. 1232, 94 L.Ed.2d 472 (1987)). Thus, the Park Owners were permitted to litigate their claims through federal court; they eventually prevailed on the “substantially advances” theory. When the Supreme Court repudiated the “substantially advances” theory in Lingle, presumably it closed this theory’s loophole in the Williamson requirements. See San Remo Hotel, L.P. v. City and County of San Francisco, 545 U.S. 323, 345-16 & n. 25, 125 S.Ct. 2491, 162 L.Ed.2d 315 (2005) (stating that Williamson did not reach “substantially advances” claims, but noting that after Lingle, such claims were foreclosed). Therefore, once Lingle was decided and the parties stipulated to vacate the first judgment of the district court and return to that court to litigate the Park Owners’ remaining claims, the ripeness of these claims was unclear. After returning to district court, the City failed to raise the issue of ripeness to the district court’s attention, and instead proceeded to defend its RCO on the merits. The district court, too, declined to raise the issue of ripeness and proceeded to grant summary judgment in favor of the City on the merits. In the parties’ filings on appeal to this court, neither party raised the issue of ripeness. Unsure of whether this case was ripe, and unsure of whether we had a duty to raise the issue ourselves, we asked the parties to discuss ripeness at oral argument. In addition to presenting the legal arguments we discuss below, the parties both represented that the Park Owners had not brought an inverse condemnation action in a California court. See generally Kavanau v. Santa Monica Rent Control Bd., 16 Cal.4th 761, 66 Cal.Rptr.2d 672, 941 P.2d 851 (1997). 1 In order to determine whether the Park Owners’s claims are ripe under Williamson, and, if so, whether they have satisfied the Williamson requirements, we must look closely at Williamson and its progeny- As the Park Owners contended at oral argument, Williamson has come under scrutiny since it was decided. Counsel for the Park Owners accused Williamson of having effectively “closed the federal courthouse doors” to litigants seeking to vindicate an important right embedded in the Fifth Amendment of the United States Constitution. He was not the first to level this accusation. In fact, the Supreme Court has already acknowledged that the practical effect of Williamson is that plaintiffs alleging violations of the Takings Clause will almost never have the opportunity to litigate their federal claims in federal court. See San Remo Hotel, 545 U.S. at 337-41, 344-48, 125 S.Ct. 2491. Williamson requires plaintiffs to go first to state court, where they are likely to generate a ruling on the merits of their takings claim from the state court that in turn will have preclusive effect should they opt to return to federal court. Id. Chief Justice Rehnquist, joined by three members of the Court, wrote specially in San Remo Hotel to explain why he believed Williamson may have been wrongly decided. See id. at 348, 352, 125 S.Ct. 2491 (Rehnquist, C.J., concurring in the judgment) (“I joined the opinion of the Court in Williamson County. But further reflection and experience lead me to think that the justifications for its state-litigation requirement are suspect, while its impact on takings plaintiffs is dramatic.”). The concurring Justices stated: Williamson County all but guarantees that claimants will be unable to utilize the federal courts to enforce the Fifth Amendment’s just compensation guarantee. The basic principle that state courts are competent to enforce federal rights and to adjudicate federal takings claims is sound, and would apply to any number of federal claims. But that principle does not explain why federal takings claims in particular should be singled out to be confined to state court, in the absence of any asserted justification or congressional directive. Id. at 351, 125 S.Ct. 2491 (citations omitted). Nevertheless, unless and until the Court decides to reconsider this issue, Williamson is the law by which we are bound. 2 Although the Court has so far declined to reconsider Williamson, it has with some frequency continued to clarify and modify the doctrine. These modifications provide the framework by which we must determine the application of Williamson to the unusual case before us. Most importantly, the Court has explicitly held that the Williamson requirements are merely prudential requirements. In Lucas v. South Carolina Coastal Council, the Court stated that the Williamson requirements were prudential: “Lucas has properly alleged Article III injury in fact in this case,” and the fact that he had not satisfied Williamson “goes only to the prudential ‘ripeness’ of Lucas’s challenge, and for the reasons discussed we do not think it prudent to apply that prudential requirement here.” 505 U.S. 1003, 1012-13, 112 S.Ct. 2886, 120 L.Ed.2d 798 (1992). Similarly, in Suitum v. Tahoe Regional Planning Agency, the Court distinguished constitutional ripeness under Article III and prudential ripeness, and stated that Williamson ripeness is grounded exclusively in prudential considerations. 520 U.S. 725, 733-34 & n. 7, 117 S.Ct. 1659, 137 L.Ed.2d 980 (1997) (stating that it was undisputed that the case “presents a genuine ‘case or controversy’ sufficient to satisfy Article III,” and considering only whether the plaintiffs case satisfied the prudential requirements). The Court itself called the Williamson requirements “prudential ripeness principles.” Id.; see also San Remo Hotel, 545 U.S. at 349, 125 S.Ct. 2491 (Rehnquist, C.J., concurring in the judgment) (noting that the Court may have purported to “divin[e]” the Williamson requirements from the text of the Fifth Amendment but later had held them to be merely prudential). The Court’s clarification that Williamson created mere “prudential requirements” is crucial to our analysis for two reasons. First, if Williamson were grounded in Article III ripeness, we would be required to raise the issue sua sponte even though neither party raised it. See Poland v. Stewart, 117 F.3d 1094, 1104 (9th Cir.1997) (“An appellate court has a duty to consider sua sponte whether an issue is ripe for review, in order to ensure that proper subject matter jurisdiction exists to hear the case.”). Because Williamson has been held to be merely a set of prudential, exhaustion-type requirements, although we asked the parties for their views, we were not obligated to raise the issue. Compare Day v. McDonough, 547 U.S. 198, 202, 205, 209-10, 126 S.Ct. 1675, 164 L.Ed.2d 376 (2006) (holding that AED-PA’s statute of limitations was akin to an exhaustion requirement, that it could be waived by the state, and that “district courts are permitted, but not obligated, to consider, sua sponte ” the issue), with John R. Sand & Gravel Co. v. United States, 552 U.S. 130, 128 S.Ct. 750, 752-54, 169 L.Ed.2d 591, (2008) (holding that the statute of limitations for cases in the United States Court of Federal Claims, 28 U.S.C. § 2501, is akin to a jurisdictional requirement, and therefore the Court of Appeals for the Federal Circuit was obligated to raise the timeliness issue despite the government’s waiver of it). As Lucas clearly illustrates, some takings cases will have undisputably satisfied Article III jurisdictional requirements but will have failed to satisfy the Williamson prudential requirements. The Court has held that where constitutional ripeness requirements have otherwise been met, a court may consider whether to excuse the failure to satisfy prudential requirements without concern of exceeding its Article III jurisdiction. Lucas, 505 U.S. at 1012-14, 112 S.Ct. 2886 (citing practical concerns to justify reaching the merits). Second, because Williamson exhaustion is prudential only, the requirement may be waived or forfeited. See Day, 547 U.S. at 202, 205, 126 S.Ct. 1675 (holding that the state may waive objections to AEDPA’s statute of limitations, which, like an exhaustion requirement, is nonjurisdictional); Queen of Angels/Hollywood Presbyterian Med. Ctr. v. Shalala, 65 F.3d 1472, 1482 (9th Cir.1995) (holding that “Medicare’s administrative exhaustion requirements are jurisdictional in nature” but may be waived by the Secretary expressly or “involuntarily, through a mistake or omission”); LaDuke v. Nelson, 762 F.2d 1318, 1323 & n. 4 (9th Cir.1985) (distinguishing between Article III and prudential standing requirements, noting that one prudential requirement was waived by the plaintiff, and finding the requirement did not bar the suit because the underlying justifications for that prudential limitation were absent); see also Zhong v. U.S. Dep’t of Justice, 480 F.3d 104, 117-25 (2d Cir.2007) (holding that issue exhaustion in the context of immigration petitions is not “truly ‘jurisdictional’ in the Article III sense” but rather a prudential administrative exhaustion requirement, and therefore that the defense may be waived and that the court has discretion to review issues not exhausted where it deems the underlying prudential concerns have been satisfied (citation omitted)). Here, in its post-Lingle filings before the district court and its filings on appeal to this court, the City of Goleta forfeited the claim that this case was not ripe for review by failing to raise it. We note that there is tension in our decisions on this point. As we recently observed, “[ajlthough the Supreme Court has described takings claims ripeness as addressing prudential rather than Article III considerations ... our Circuit has analyzed takings claim ripeness as raising both prudential and Article III considerations.” McClung v. City of Sumner, 548 F.3d 1219, 1224 (9th Cir.2008) (citing cases). In particular, there is tension between language in three of our decisions. In Hacienda Valley Mobile Estates v. Morgan Hill, 353 F.3d 651 (9th Cir.2003), we concluded that “[b]ecause ... Hacienda’s claim is not ripe, we affirm the district court’s dismissal for lack of subject matter jurisdiction.” Id. at 661. In that case, we did not otherwise discuss whether Williamson embraced both jurisdictional and prudential requirements, nor did we discuss the impact on Williamson of Palazzolo, Suitum, or Lucas. By contrast, in Richardson v. City & County of Honolulu, 124 F.3d 1150 (9th Cir.1997), we recited that “[i]f a claim is unripe, federal courts lack subject matter jurisdiction and the complaint must be dismissed,” and we then determined that the landowners’ takings claim was “not ripe” and “premature.” Id. at 1160, 1161-62 (quotation marks and citation omitted), 1162. Although the claim was not ripe under Williamson, we reached the merits anyway and upheld the constitutionality of the ordinance. Id. at 1166. We thus treated the ripeness inquiry as prudential only. In our latest effort in this area, McClung v. City of Sumner, we noted the conflict in our cases and then treated the jurisdictional concerns as an aspect of Article III and the prudential concerns as the sole inquiry under Williamson. 548 F.3d at 1224 (“[W]e do not resolve whether this claim is ripe under the standards articulated in Williamson, and instead assume without deciding that the takings claim is ripe in order to address the merits of the appeal.”). In light of the Supreme Court’s unmistakable pronouncements, we think that McClung and Richardson represent the more considered view. In this case, as in McClung, there is no question that the Park Owners have satisfied Article III requirements, including ripeness. We have held, in another context, that “the [Article III] ripeness inquiry contains both a constitutional and a prudential component.” Thomas v. Anchorage Equal Rights Comm’n, 220 F.3d 1134, 1138 (9th Cir.2000) (en banc) (emphasis added); see also Colwell, 558 F.3d at 1123 (“[RJipeness doctrine reflects both constitutional and prudential considerations.”). We stated in Thomas that the Article III component of the ripeness inquiry “can be characterized as standing on a timeline,” and that the real question in cases presenting questions of Article III ripeness is whether “there exists a constitutional ‘case or controversy,’ [and] that the issues presented are ‘definite and concrete, not hypothetical and abstract.’ ” 220 F.3d at 1138, 1139 (quotations omitted). See also Colwell, 558 F.3d at 1123. Where it is clear that a takings plaintiff has standing — including “standing on a timeline” — and has “presentera genuine case or controversy sufficient to satisfy Article III,” the further questions under Williamson of whether a plaintiff has “received a final decision regarding the application of the challenged regulations to the property at issue” and whether the he has “sought compensation through the procedures the State has provided for doing so” are merely “prudential ripeness requirements.” Suitum, 520 U.S. at 733 n. 7, 734, 117 S.Ct. 1659 (internal alterations and quotation marks omitted). In this case, then, where the Park Owners have obviously presented a live case or controversy, see supra Part II.A, it is clear that any further questions under Williamson do not raise the spectre of an Article III jurisdictional bar. See Colwell, 558 F.3d at 1123 (noting that because “[pjlaintiffs’ stake in the legal issues is concrete rather than abstract ... the ripeness requirement of Article III is satisfied.”). 3 Having reviewed the Williamson jurisprudence, we find that we may reach the merits of the Park Owners’ takings claim. For the following reasons, “we do not think it prudent to apply that prudential requirement here.” Lucas, 505 U.S. at 1013, 112 S.Ct. 2886. First, the City forfeited its claim that the case was not ripe for decision. Because the Williamson requirements are “prudential ripeness principles,” Suitum, 520 U.S. at 733-34, 117 S.Ct. 1659, and not Article III jurisdictional limitations, they may be waived or forfeited. After Lingle prompted the parties to stipulate to vacate the initial judgment of the district court and return for litigation at the trial level, the City had the burden to raise any remaining prudential concerns under Williamson. Instead, the City was content to continue litigating the claims on the merits. The City expressed no doubts that the record in the case was fit for a decision by a federal court. Moreover, the City was not concerned that the Park Owners’ failure to initiate an inverse condemnation action in state court left any doubt as to whether the state had yet compelled the City to provide just compensation to the Park Owners. The City did not, in fact, mention ripeness at all until prompted by an order from this court to discuss the issue at oral argument. At oral argument, the City acknowledged that as part of its appeal it had not even considered whether Williamson prevented us from reaching the Park Owners’ takings claims, and first came to the position that Williamson did so after receiving our order to be prepared to discuss Williamson at oral argument. The City argued to us that the case was not ripe under Williamson, and offered as supporting authority our opinions in Equity Lifestyle Properties and Carson Harbor Village. Neither of these cases, nor in fact Williamson itself, appeared in the City’s appellate brief. In answer to our questions, the City expressly conceded that the Williamson requirements were merely prudential and not Article III jurisdictional requirements. The City argued that its claim was not waived because we could still exercise our discretion to find that the case was not ripe because of prudential considerations. The City’s argument lacks merit, however. Because the Williamson requirements are merely prudential, the claims can be waived. The fact that we may exercise our discretion to find the claims unripe does not change the fact that the claims are waivable, and that in this case the City forfeited them. The fact that the City forfeited its ripeness claim has an additional, evidentiary implication. It confirms our belief that the record in this case is eminently ripe for review. Williamson could have resurfaced at the time that Lingle implicitly foreclosed the Park Owners’ exception from Williamson based on the “substantially advances” theory. It did not. It would certainly seem counter-intuitive to us now to think that a case that had at that point already been litigated through three rounds — two in federal court and one in state court — could suddenly become “unripe.” The fact that the City failed to notice this as well suggests to us that any concerns meant to be protected by Williamson had been sufficiently protected by the unusual and lengthy development of the case. See Palazzolo, 533 U.S. at 622, 121 S.Ct. 2448 (holding that the purpose of Williamson is to develop the record in order to understand the effect of the challenged regulation). Second, we find that the Park Owners have substantially satisfied the Williamson requirements. “[I]t is important to bear in mind the purpose” that the Williamson requirement serves. Id. at 622, 121 S.Ct. 2448. Williamson held that a facial takings claim could not be ripe until the property owner has “unsuccessfully attempted to obtain just compensation through the procedures provided by the State for obtaining such compensation.” 473 U.S. at 195, 105 S.Ct. 3108. Here, the Park Owners did, in fact, take this case to state court. Although they did not file a formal inverse condemnation proceeding, they litigated and settled several state law issues relevant to the alleged taking with the City, including issues necessary to establish the timeliness of the takings claim. They then returned to federal court, without having been compensated for the taking of their property. There is no doubt that they have now unsuccessfully attempted to obtain just compensation through procedures provided by the State. See id. Moreover, there is just no question that the case is fit for review. The parties have now litigated this case through three full rounds at the trial court level. There is no doubt that there is sufficient evidence in the record to “determine whether [the] regulation goes ‘too far.’ ” Palazzolo, 533 U.S. at 622, 121 S.Ct. 2448 (quoting MacDonald, 477 U.S. at 348, 106 S.Ct. 2561). In addition, as we discuss below, it is undisputed that: (1) the RCO has caused a significant loss of value to the Park Owners’ property; and (2) neither the City of Goleta nor the State of California has ever offered compensation for this loss in value. To the contrary, the City has litigated against providing compensation continuously since 2002. Given the Park Owners’ substantial compliance with the Williamson requirements, and the City’s forfeiture of the ripeness claim, we believe that Lucas compels us to reach the merits of this case. “In these circumstances, we think it would not accord with sound process to insist that [the Park Owners] pursue the late-created” need to file a formal inverse condemnation action in state court “before [their] takings claim can be considered ripe.” Lucas, 505 U.S. at 1012, 112 S.Ct. 2886. Just like Lucas, the Park Owners “[have] properly alleged Article III injury in fact in this case.” Id. Any failure to have filed a formal inverse condemnation claim while already in state court “goes only to the prudential ‘ripeness’ of [the Park Owners’] challenge, and for the reasons discussed we do not think it prudent to apply that prudential requirement here.” Id. at 1013. Ill Having held that we may reach the merits of the Park Owners’ takings claims, we now turn to those claims. As we have recently summarized, the Supreme Court has identified three basic categories of regulatory takings claims: [1] where government requires an owner to suffer a permanent physical invasion of property, see Loretto v. Teleprompter Manhattan CATV Corp., 458 U.S. 419, 102 S.Ct. 3164, 73 L.Ed.2d 868 (1982); [2] where a regulation deprives an owner of all economically beneficial use of property, see Lucas v. South Carolina Coastal Council, 505 U.S. 1003, 112 S.Ct. 2886, 120 L.Ed.2d 798 (1992); and [3] where the Penn Central factors are met, Penn Central Transp. Co. v. New York City, 438 U.S. 104, 98 S.Ct. 2646, 57 L.Ed.2d 631 (1978). Crown Point Dev., Inc. v. City of Sun Valley, 506 F.3d 851, 855 (9th Cir.2007); see Lingle, 544 U.S. at 538, 125 S.Ct. 2074. On appeal, the Park Owners raise only a facial challenge under Penn Central. As described in Lingle, The Court in Penn Central acknowledged that it had hitherto been unable to develop any set formula for evaluating regulatory takings claims, but identified several factors that have particular significance. Primary among those factors are the economic impact of the regulation on the claimant and, particularly, the extent to which the regulation has interfered with distinct investment-backed expectations. In addition, the character of the governmental action— for instance whether it amounts to a physical invasion or instead merely affects property interests through some public program adjusting the benefits and burdens of economic life to promote the common good — may be relevant in discerning whether a taking has occurred. The Penn Central factors— though each has given rise to vexing subsidiary questions — have served as the principal guidelines for resolving regulatory takings claims that do not fall within the physical takings or Lucas rules. 544 U.S. at 538-39, 125 S.Ct. 2074 (internal quotation marks and citations omitted). We must first address each factor in turn, and then weigh the factors together, in what has famously been described as an “essentially ad-hoc, factual inquir[y].” Penn Central, 438 U.S. at 124, 98 S.Ct. 2646. Before we can apply the Penn Central factors, however, we must consider the viability of a facial challenge under Penn Central, and determine what facts we may consider when engaging in Penn Central’s ad-hoc factual inquiry. A The Park Owners have brought only a facial challenge to the RCO under Penn Central — they have not brought a corollary as-applied claim. Unlike an as-applied challenge, which asserts that a statute or regulation “by its own terms, infringe[s] constitutional freedoms in the circumstances of the particular case,” United States v. Christian Echoes Nat’l Ministry, Inc., 404 U.S. 561, 565, 92 S.Ct. 663, 30 L.Ed.2d 716 (1972), a facial challenge alleges that the statute or regulation is unconstitutional in the abstract: that “no set of circumstances exists under which the [a]ct would be valid.” United States v. Salerno, 481 U.S. 739, 745, 107 S.Ct. 2095, 95 L.Ed.2d 697 (1987). The Park Owners’ decision to refrain from an as-applied challenge has two important consequences. First, as noted above, the decision exempts the Park Owners from the “final decision” prong of Williamson. See Hacienda Valley Mobile Estates, 353 F.3d at 655 (“Facial challenges are exempt from the [“final decision”] prong of the Williamson ripeness analysis because a facial challenge by its nature does not involve a decision applying the statute or regulation.”). Second, the Park Owners’ decision to cast their Penn Central claim as a facial challenge places limits on the types of evidence that can be considered in adjudicating the claim. “In facial takings claims, our inquiry is limited to ‘whether the mere enactment of the [regulation] constitutes a taking.’ ” Tahoe-Sierra Pres. Council, Inc. v. Tahoe Reg’l Planning Agency, 216 F.3d 764, 773 (9th Cir.2000) (quoting Agins, 447 U.S. at 260, 100 S.Ct. 2138); see also Hodel v. Va. Surface Mining & Reclamation Ass’n, 452 U.S. 264, 295, 101 S.Ct. 2352, 69 L.Ed.2d 1 (1981). More specifically, in a facial challenge “we look only to the regulation’s general scope and dominant features, rather than to the effect of the application of the regulation in specific circumstances.” Tahoe-Sierra, 216 F.3d at 773 (internal quotation marks and citation omitted). For this reason, the Supreme Court has noted that property owners bringing a facial takings challenge “face an uphill battle.” Suitum, 520 U.S. at 736 n. 10, 117 S.Ct. 1659; see Keystone, 480 U.S. at 495, 107 S.Ct. 1232. The fact that the Park Owners have characterized their facial challenge under Penn Central creates further complications. In a typical Penn Central claim, the court must consider factors that will usually not be found in the text of the statute, such as the economic impact on the claimant and the claimant’s investment-backed expectations. Nevertheless, when adjudicating a facial challenge, the court must be careful not to simply look at “the effect of the application of the regulation in specific circumstances.” Tahoe-Sierra, 216 F.3d at 773. The Park Owner’s facial Penn Central claim requires us to address this apparent paradox: we must confront the question of whether a facial challenge under Penn Central is actually a viable legal claim; and if we determine that it is, we must then consider what evidence the Park Owners may present to prove their claim. 1 In the district court’s summary judgment ruling of April 5, 2006, the court reviewed the record and engaged in a detailed Penn Central analysis. Each party had proffered an expert report in support of its position: the Park Owners proffered a report by Dr. John M. Quigley, and the City responded with a report by Mr. William Thomsen. In its April ruling, although the district court did not rely on the detailed figures presented in either report, the district court did credit the core findings of each report (which we discuss infra). The district court found in favor of the City under Penn Central. Subsequently, the district court issued another summary judgment ruling on September 6, 2006, in which it purported to address the Park Owners’ remaining claims. The district court then reaffirmed its ruling that the Park Owners had not prevailed under Penn Central. The district court’s ruling was ambiguous, however, as to the basis for its decision. The court was unclear as to whether it was simply re-incorporating and reaffirming the Penn Central analysis applied in its April ruling, or whether it now based its ruling on the new ground that the Park Owners were precluded from presenting any of the evidence the court had relied on in April because the Park Owners brought only a facial challenge. The district court stated that the evidence the Park Owners sought to present “at trial” was “irrelevant” to a facial challenge, and complained that the Park Owners had “impermissibly attempted to convert this action, de facto, into an as-applied challenge.” Because of the necessarily “ad hoc” nature of a Penn Central challenge, if the district court was adopting a rule that a property owner may present no evidence of the effect of a regulation on his property in a facial challenge, the court would essentially be adopting the rule that there is no such thing as a facial challenge under Penn Central. Similarly, the City’s position to our court on the meaning of a facial Penn Central challenge is ambiguous. The City has never argued that a facial challenge under Penn Central is not a viable legal claim. On the contrary, the City devoted much of its briefing and oral argument to defending the district court’s April ruling on the Park Owners’ Penn Central facial challenge, including the court’s reliance on the core conclusions of the two parties’ expert reports. In defending the conclusion of the district court on appeal, the City argues: [T]he district court concluded that absent the Ordinance, Park Owners would have achieved higher rates of return. This conclusion credits Park Owners’ economic evidence and essentially agreed with Park Owners that the Ordinance had an economic impact on their business operation. It is difficult to imagine how the court’s analysis and conclusion regarding the Ordinance’s economic impact can be found lacking. Elsewhere in its brief, however, the City complains that the Park Owners have introduced so much evidence as to try to turn a facial challenge into an as-applied challenge. The City does not point out which evidence is proper and which is impermissible in a facial challenge. Both logic and Supreme Court precedent support our conclusion that a facial challenge under Penn Central must exist as a viable legal claim. Certainly it is apparent that a facial challenge is easier to mount under either Loretto or Lucas. It is far easier to prove that a regulation effects a physical invasion or that it denies an owner of all economically viable use of his property without considering evidence beyond the face of the regulation than it is to demonstrate that the regulation’s effect satisfies the multi-factor test of Penn Central. However, we have recently described the Loretto and Lucas tests as categorical “exceptions to the application of the regulatory takings test” as set forth in Penn Central. Scheehle v. Justices of the Sup.Ct. of Ariz., 508 F.3d 887, 894 (9th Cir.2007); see Lingle, 544 U.S. at 538, 125 S.Ct. 2074 (“Outside these two relatively narrow categories ..., regulatory takings challenges are governed by the standards set forth in Penn Central.”). In fact, the Supreme Court has emphasized that per se takings claims are disfavored, whereas Penn Central claims are preferred. See Tahoe-Sierra Pres. Council, Inc. v. Tahoe Reg’l Planning Agency, 535 U.S. 302, 321, 339, 342, 122 S.Ct. 1465, 152 L.Ed.2d 517 (2002). It would seem incongruous indeed if only the disfavored exceptions to Penn Central could be brought as facial challenges, where a claim under the general rule of Penn Central could not. Supreme Court precedent also demonstrates the viability of a facial challenge under Penn Central. In Keystone, the Court emphasized the difficulty of prevailing on a facial challenge under Penn Central, and ultimately concluded that the mere enactment of the challenged statute did not effect a taking. See Keystone, 480 U.S. at 493-99, 107 S.Ct. 1232. The Court’s ruling implicitly recognizes that a facial Penn Central challenge is feasible. Moreover, in Keystone, the Court considered the limited evidence that the property owners had proffered, including the actual tonnage of coal that the challenged statutes prevented the owners from removing, and the percentage of total coal in the mine that the restricted tonnage represented. See id. at 496-99 & n. 24, 107 S.Ct. 1232. The Court found that the property owners’s facial challenge under Penn Central failed because the evidence the property owners provided was insufficient to demonstrate economic harm in any significant amount. Id. Thus, the Court found against the property owners not because the Court was not permitted to consider the evidence provided, but rather because the property owners’ evidence did not show that the mere enactment of the statute amounted to a taking. Keystone suggests that a facial Penn Central challenge is difficult, but viable. Similarly, in Connolly v. Pension Benefit Guaranty Corp., the Court considered and rejected a facial Penn Central challenge to the withdrawal liability provisions of the Multiemployer Pension Plan Amendments Act of 1980. 475 U.S. 211, 213, 224-28, 106 S.Ct. 1018, 89 L.Ed.2d 166 (1986); see also Tahoe-Sierra, 535 U.S. at 321, 122 S.Ct. 1465 (holding that the property owners’ facial takings claim should have been brought under Penn Central); Hodel, 452 U.S. at 294-97, 101 S.Ct. 2352 (ruling on a facial challenge under Penn Central). Keystone and Connolly demonstrate that a facial challenge under Penn Central may be difficult, but the mere fact that Penn Central requires an ad-hoe multi-factor balancing test does not bar a facial challenge. 2 The fact that the Court’s precedents approve of a facial challenge under Penn Central requires us to consider what kinds of evidence beyond the text of the challenged regulation the reviewing court may consider. A facial challenge seeks to prove that “the ‘mere enactment’ of the [regulation] constitutes a taking.” Keystone, 480 U.S. at 495, 107 S.Ct. 1232 (quoting Hodel, 452 U.S. at 295, 101 S.Ct. 2352). Property owners “thus face an uphill battle in making a facial attack on [a regulation] as a taking.” Id. at 495, 107 S.Ct. 1232. In reviewing a facial challenge under the Takings Clause, we “look only to the regulation’s general scope and dominant features, rather than to the effect of the application of the regulation in specific circumstances.” Tahoe-Sierra, 216 F.3d at 773 (quotation marks omitted). In a takings case, however, we are cognizant that the text of the regulation i