Opinion of the Court
“shall designate critical habitat… after taking into consideration the economic impact, the impact on national security, and any other relevant impact, of specifying any particular area as critical habitat. The Secretary may exclude any area from critical habitat if he determines that the benefits of such exclusion outweigh the benefits of specifying such area… unless he determines… that the failure to designate such area as critical habitat will result in the extinction of the species concerned.” 16 U. S. C. §1533(b)(2).
Although the text meanders a bit, we recognized in Bennett v. Spear, 520 U. S. 154 (1997), that the provision describes a unified process for weighing the impact of designating an area as critical habitat. The first sentence of Section 4(b)(2) imposes a “categorical requirement” that the Secretary “tak[e] into consideration” economic and other impacts before such a designation. Id., at 172 (emphasis deleted). The second sentence authorizes the Secretary to act on his consideration by providing that he may exclude an area from critical habitat if he determines that the benefits of exclusion outweigh the benefits of designation. The Service followed that procedure here (albeit in a flawed manner, according to Weyerhaeuser). It commissioned a report to estimate the costs of designating the proposed critical habitat, concluded that those costs were not “disproportionate” to the benefits of designation, and “[c]onsequently” declined to “exercis[e] [its] discretion to exclude any areas from [the] designation of critical habitat.” App. 190.
Bennett explained that the Secretary’s “ultimate decision” to designate or exclude, which he “arriv[es] at” after considering economic and other impacts, is reviewable “for abuse of discretion.” 520 U. S., at 172. The Service dismisses that language as a “passing reference… not necessarily inconsistent with the Service’s understanding,”
