From a speech by WTO DG Pascal Lamy:
Growing interdependence among nations, as well as growing consumer awareness, have certainly focused greater attention on NTMs [non-tariff measures]. As the use of NTMs increases, the potential for friction is likely to increase. A number of high-profile disputes have already arisen around public policy measures. The SPS and TBT agreements go beyond non-discrimination and include the need to ensure that measures are not unnecessarily trade restrictive. As has been made clear by recent decisions of the Appellate Body, this can involve WTO adjudicators being called upon to assess the legitimacy of the objectives that a member pursues through domestic regulation, and to scrutinize the regulatory choices and distinctions that it makes in seeking to achieve those objectives. Some question the appropriateness of adjudicators having to do this, and ask, more generally, how the line should be drawn between an inappropriate inquiry into government motivation and an appropriate assessment of measures that have trade effects and that are challenged by other members.
I'm a little puzzled by this last sentence. Why is an "inquiry into government motivation" called "inappropriate" and an "assessment of measures that have trade effects" called "appropriate"? Or am I reading this wrong? There is little doubt that both "motivation" and "effects" can be controversial and sensitive issues, and we need to think carefully about how this analysis should be carried out. To me, though, the main source of the problem is where the rules prohibit measures due to their "trade effects" in situations where the measures affect both domestic and foreign products/producers equally.