From the EC - Seal Products panel report:
7.292. The European Union points out that the protection of the economic and social interests of Inuit or indigenous communities is recognized at the international level as illustrated, for example, in the United Nations Declaration on the Rights of Indigenous Peoples (UN Declaration) and in the ILO Convention concerning Indigenous and Tribal Peoples in Independent Countries (ILO Convention).
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7.295. In our view, these sources, taken in their entirety as factual evidence475, ...
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475 In taking into account the recognition given by international instruments in the context of the United Nations and the ILO to the interests of Inuit and indigenous communities, the Panel is mindful that these instruments are not WTO instruments and they do not set out WTO obligations per se. We are considering the content of these instruments as part of the evidence submitted by the European Union to support its position concerning the interests of Inuit and indigenous communities, not as legal obligations of Members.
There are a number of aspects of the role of international law in WTO dispute settlement that are controversial, but the panel's statements here seem sensible to me: International legal instruments can be used as factual evidence in the context of applying specific WTO legal provisions.
