Labelling schemes are market tools that are more and more frequently used to attract consumers through information on the environmental and social friendliness of products, thus promoting sustainable production and consumption. The TBT Agreement of the WTO system considers their consistency with free trade, combining the latter with the respect of non-trade values. The TBT rules together with the relevant WTO case law are recalled by the new generation of FTAs: they therefore represent the parameter of international legitimacy for mandatory, voluntary, public and private labelling schemes, which are constantly discussed as STCs within the important TBT Committee.