Legal Sidebari

Home is Where the Habitat is: Supreme Court
Addresses Critical Habitat under the
Endangered Species Act
December 19, 2018
On November 27, 2018, in a unanimous decision, the Supreme Court held that only “habitat” of an
endangered species can be designated as “critical habitat” under the Endangered Species Act (ESA).
(Justice Kavanaugh did not participate in the decision.) The case, Weyerhauser Co. v. U.S. Fish and
Wildlife Service, involved the Fish and Wildlife Service’s (FWS’s or Service’s) decisions (1) to designate
a 1,544-acre private property as critical habitat for the endangered dusky gopher frog, and (2) not to
exclude the property from its critical habitat designation. The Court remanded the case to the U.S. Court
of Appeals for the Fifth Circuit (Fifth Circuit) to determine whether the private property was “habitat” for
the frog and if the FWS abused its discretion when it decided not to exclude the property from the critical
habitat designation.
Although the Supreme Court did not define “habitat” under the ESA, its ruling is significant because it
clarifies that, in order to be deemed “critical habitat,” an area must first meet the requirements to be
deemed “habitat” for the endangered species. Further, the Court’s decision opens the door to judicial
review of the FWS’s discretion not to exclude property from its “critical habitat” designations. This
Sidebar explains the criteria for designating critical habitat under the ESA, reviews the critical habitat
designation for the dusky gopher frog, and discusses the Weyerhauser Co. decision and the importance of
the case moving forward.
Designating Critical Habitat under the ESA
Congress enacted the ESA to conserve endangered species and their habitats. For each species listed as
threatened or endangered under the ESA, the Secretary of the Interior (through the FWS) must “designate
any habitat of such species which is then considered to be critical habitat.” The ESA authorizes the FWS
to designate two types of critical habitat: (1) specific areas within the geographical area occupied by the
species, which contain the “physical or biological features essential to the conservation of the species”
and may require special management protections (occupied habitat); and (2) areas outside the
geographical areas occupied by the species if the Secretary determines that such unoccupied areas are
“essential for the conservation of the species” (unoccupied habitat).
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The ESA requires the FWS to base its critical habitat designation on the “best scientific data available”
and consider the “economic impact” and other relevant impacts of the designation. FWS may exclude an
area that would otherwise be included as critical habitat if the benefits of exclusion outweigh the benefits
of designation, unless the exclusion would result in the extinction of the species.
Once an area is designated as critical habitat, federal agencies may not authorize, fund, or carry out
actions that are likely to “result in the destruction or adverse modification” of critical habitat. If FWS
determines that an agency action, such as issuing a permit, would harm critical habitat, the agency must
terminate the action, implement an FWS-proposed action, or seek an exemption. A critical habitat
designation does not directly affect private landowners. However if the development of their land requires
a federal permit, authorization, funds, or other federal action, a critical habitat designation could affect
their activities.
The Endangered Dusky Gopher Frog and its Critical Habitat
After listing the dusky gopher frog as an endangered species in 2001, the FWS designated four areas in
Mississippi totaling 4,933 acres as occupied critical habitat in 2012. The Service concluded that these
occupied areas possessed the three features that the Service considered “essential to the conservation” of
the frog and required special protection: (1) ephemeral ponds (seasonally flooded and isolated from other
water bodies) for breeding; (2) upland, open-canopy forest containing holes and burrows for dwelling;
and (3) open-canopy forest that allows the frog to move between breeding and dwelling areas.
Because the FWS determined that the four designated areas in Mississippi would not be adequate to
ensure the frog’s conservation, the Service also designated as unoccupied critical habitat 1,544 acres in St.
Tammary Parish, Louisiana (Unit 1). The dusky gopher frog does not currently occupy the land in Unit 1
and according to the FWS, has not been seen in the unit since 1965. However, Unit 1 contains five
ephemeral ponds suitable for the frog’s breeding. Although the closed-canopy timber plantation areas of
Unit 1 does not contain the “essential physical or biological features of critical habitat,” the Service
determined that an open-canopy forest could be restored “with reasonable effort.” The Service concluded
that Unit 1 is essential for the conservation of the frogs because it provides important and rare breeding
sites for recovery of the endangered frog.
The FWS also decided not to exclude Unit 1 from its critical habitat designation because the costs of
designating the areas, including Unit 1, were not “disproportionate” to the conservation benefits.
Weyerhauser Co. v. U.S. Fish and Wildlife Service Decision
The Supreme Court’s decision in Weyerhauser Co. clarified two issues related to the designation of
critical habitat under the ESA. First, the Supreme Court held that, as a threshold matter, the FWS must
determine if an area is “habitat” before it may consider whether it is “critical habitat.” In this case, the
plaintiffs challenged the critical habitat designation, arguing that Unit 1 could not be critical habitat for
the dusky gopher frog because Unit 1 was not a habitat for the frog without the other essential habitat
features such as open canopy areas. The Fifth Circuit rejected the argument that the definition of “critical
habitat” contains any “habitability requirement.” The Fifth Circuit held that the FWS reasonably
concluded that Unit 1 was essential for the conservation of the frog, deferring to the FWS’s interpretation
of the term “essential” under the ESA.
On review, the Supreme Court disagreed with the Fifth Circuit, reasoning that “[a]ccording to the
ordinary understanding of how adjectives work, . . . ‘critical habitat’ is the subset of ‘habitat’ that is
‘critical’ to the conservation of an endangered species.” In analyzing the ESA statutory language, the
Court held that the ESA “does not authorize the Secretary [of the Interior] to designate the area as critical
habitat unless it is also habitat for the species.” However, the Court noted that the ESA does not define
“habitat.” Because the Fifth Circuit held that “critical habitat” was not limited to areas that qualified as

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habitat, the Court vacated the judgment and instructed the Fifth Circuit on remand to interpret the term
“habitat” and assess whether Unit 1 qualified as “habitat” that was critical to the conservation of the
dusky gopher frog.
Second, the Supreme Court clarified that the FWS’s decision not to exclude an area as critical habitat is
judicially reviewable. The plaintiffs challenged the FWS’s decision not to exclude Unit 1 from the dusky
gopher frog’s critical habitat, arguing that the Service had failed to weigh adequately the benefits of
designating Unit 1 against the economic impact of the designation. The Fifth Circuit did not address this
claim because it concluded the ESA provides the FWS with the discretion to decide not to exclude an area
from critical habitat. Because the ESA provided no standard to review FWS’s discretionary decision not
to exclude Unit 1, the Fifth Circuit held that it was not reviewable. The Supreme Court disagreed, holding
that a challenge to FWS’s cost-benefit analysis is the “sort of claim that federal courts routinely assess
when determining whether to set aside an agency decision as an abuse of discretion” under the
Administrative Procedure Act. The Court vacated the judgment and instructed the Fifth Circuit to
consider whether the Service’s cost-benefit assessment and its decision to not exclude Unit 1 from the
critical habitat designation was arbitrary, capricious, or an abuse of discretion in violation of federal
rulemaking requirements (discussed in this Report).
Implications
While acknowledging that the ESA does not provide a “baseline definition of habitat,” the Supreme Court
left the task to the lower court to interpret the term “habitat.” Without a statutory definition or guidance
from the Court, the Fifth Circuit may defer to the FWS’s interpretation of “habitat” in light of its previous
decision in this case that deferred to the Service’s interpretation of what is considered “essential” to the
conservation of the endangered dusky gopher frog. The FWS has argued that “habitat” can include areas
like Unit 1 that would require reasonable modifications to support a sustainable population of the
endangered species.
A narrow interpretation of “habitat” by the court could potentially limit the government’s ability to
designate areas as critical habitat and affect the conservation and recovery of an endangered species. For
example, if Unit 1 is designated as critical habitat, the ESA requires federal agencies issuing permits for
land development to consult with the FWS and, if necessary, prescribe conditions or changes to the
projects to prevent destruction or adverse modification of the critical habitat. Without a critical habitat
designation, federal agencies would not be required to initiate ESA consultations for Unit 1 land
development and could not impose conservation measures identified through consultation.
Further, the Supreme Court’s ruling opens the door to future challenges to the FWS’s decision not to
exclude areas from its critical habitat designations. Before Weyerhauser Co., the Fifth Circuit and other
lower courts that addressed this issue had held that the FWS’s decision not to exclude an area from
critical habitat is not subject to judicial review.
While the case is remanded to the Fifth Circuit, the Supreme Court’s decision in Weyerhauser
Co. could inform congressional efforts and debate on the definition of “habitat” under the ESA
and how the FWS assesses costs and benefits of its critical habitat designations. In addition, the
Trump Administration may finalize its proposal to narrow the scope of the FWS’s authority to
designate unoccupied habitat by adding additional criteria. The proposal, among other things,
would allow the Secretary of the Interior to designate unoccupied areas as critical habitat if the
occupied habitat of the species at the time of listing is inadequate to ensure the conservation of
the species or results in less efficient conservation of the species than habitat that includes
unoccupied areas. Under the proposal, for an unoccupied area to be “essential” for the

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conservation of the species, the Secretary would first need to determine that there is a likelihood
that the area would contribute to the conservation of the species.

Author Information

Linda Tsang

Legislative Attorney




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