U.S. Department of Commerce


Date of this Version



Conservation Biology, Volume 22, No. 4, 1075–1077; DOI: 10.1111/j.1523-1739.2008.00980.x


After many years of experiencing relatively benign neglect, the language in the U.S Endangered Species Act (ESA) that deals with risks to a species in a “significant portion of its range” (SPOIR) has attracted a great deal of recent attention from legal and biological perspectives (Defenders of Wildlife v. Norton 2001; Center for Biological Diversity v. U.S. Fish and Wildlife Service 2007; Vucetich et al. 2006; Nelson et al. 2007; Waples et al. 2007a, 2007b). In the latest commentary on this topic, D’Elia et al. (2008) make 3 major points: (1) when evaluating such language, it is important to consider relevant legal decisions, (2) in our recent paper on SPOIR (Waples et al. 2007a), we ignored this step and consequently the framework we proposed is legally flawed, and (3) societal values should be considered along with biological criteria in evaluating the SPOIR language. On the first point, we believe we are in agreement. Regarding the second point, although it is true we did not attempt a detailed evaluation of case law on SPOIR, it is not true that we ignored the decisions of record. Rather, we considered these cases and concluded they provide little conclusive guidance about how to interpret the SPOIR language. We have discussed the SPOIR language and related court decisions with a number of government and private-sector lawyers, and we found no strong consensus on their import. As a consequence, and in response to a request from policy makers within our agency, we sought to develop a biological framework for interpreting the SPOIR language on the basis of biological principles consistent with existing case law.

We strongly disagree with the statements by D’Elia et al. (2008) about the relationship between our proposed framework and the Ninth Circuit Court of Appeals’ decision regarding the case of the flat-tailed horned lizard (Defenders of Wildlife v. Norton 2001). In that case (p. 9660), the Court summarized the position of the Secretary of the Interior as follows:

The Secretary in her brief interprets the enigmatic phrase to mean that a species is eligible for protection under the ESA if it “faces threats in enough key portions of its range that the entire species is in danger of extinction, or will be within the foreseeable future.” She therefore assumes that a species is in danger of extinction in “a significant portion of its range” only if it is in danger of extinction everywhere.

Not surprisingly, the Court concluded that this interpretation was arbitrary and capricious because it would render the phrase “or a significant portion of its range” entirely superfluous. If something can occur if either a or b is true, but b = a, then there is only a single choice and the “or” clause is robbed of any real power. Our SPOIR framework does not suffer from this flaw because it is designed to cover situations only when the entire species is not currently at risk in its entire range. Figure 2 of Waples et al. (2007a) illustrates several situations in which a listing under our SPOIR framework could occur; none of these scenarios would allow a listing if the SPOIR language were omitted from the statute. Therefore, our framework clearly gives “independent and separate meaning to the clauses that appear on either side of the word or” (a criterion proposed by D’Elia et al. 2008).