European Communities—Measures Prohibiting the Importation and Marketing of Seal Products is the first case in which the dispute system of the World Trade Organization (WTO) has wrestled with a regulation that pursued multiple conflicting, legitimate purposes. (I will explain later why Brazil—Retreaded Tyres is not such a case.) This generates puzzles about applying the definition of a “technical regulation” to complex measures; about whether an exception to a ban can be justified by a purpose different from that of the ban; and about how to apply “less restrictive alternative” analysis to measures with multiple goals. The first of these puzzles is unique to the Agreement on Technical Barriers to Trade (TBT); the second and third concern the TBT, the General Agreement on Tariffs and Trade (GATT), and probably other agreements.
Regan, Donald H. "Measures with Multiple Purposes: Puzzles from EC-Seal Products." AJIL Unbound 108 (2015): 315-22.