to a decision not to designate critical habitat. But the statute cannot be read to say that the FWS is ever obligated to exclude habitat that it has found to be essential. Such a decision is always discretionary and the statute “provides absolutely no standards that constrain the Service’s discretion” not to exclude, unlike the statute reviewed in Amador County, which cab-ined the agency’s discretion to disapprove compacts to a set of specified conditions. See Conservancy of Sw. Fla. v. U.S. Fish and Wildlife Serv., 677 F.3d 1073, 1084, n. 16 (11th Cir.2012) (distinguishing Amador County and finding that the use of the word “may” in another section of the ESA precludes the review of an agency’s exercise of discretion); see also Ekimian v. INS, 303 F.3d 1153, 1159 (9th Cir.2002) (<HOLDING>). Accordingly, we affirm the district court’s
holding that such a threat would not supply exceptional circumstances holding that where the board of immigration is permitted to reopen proceedings in exceptional circumstances its decision not to reopen a case is unreviewable because there are no statutory regulatory or caselaw definitions of exceptional circumstances  and  thus no manageable standard to apply on review holding the court should only apply the doctrine narrowly and only under exceptional circumstances holding hardship is discovered in the rare case based on exceptional circumstances holding in the absence of exceptional circumstances deference should be given to trial court