Castaneda v. Souza, ___ F.3d ___, ___, 2014 WL 4976140 (1st Cir. Oct. 30, 2014) (Since Justice Kennedys vote was necessary to the majority, his limiting rationale is binding on us.4 fn4 See Bruno & Stillman, Inc. v. Globe Newspaper Co., 633 F.2d 583, 594-95 (1st Cir. 1980) (construing the Supreme Courts 5-4 decision in Branzburg v. Hayes, 408 U.S. 665 (1972), to be limited by the concurring opinion of Justice Powell); accord, e.g., United States v. Smith, 135 F.3d 963, 968-69 (5th Cir. 1998); see also United States v. District of Columbia, 654 F.2d 802, 806-07 (D.C. Cir. 1981) (giving similar treatment to National League of Cities v. Usery, 426 U.S. 833 (1976), in light of Justice Blackmuns necessary concurrence).