This paper assesses the "Report on the Appellate Body of the World Trade Organization," published by the U.S. Trade Representatives in February 2020. In particular, this paper examines the U.S. critique of the Appellate Body's interpretation of the non-discrimination obligation under the TBT Agreement and the GATT 1994 in the USTR's Report. The critique in the report was written against the backdrop of the "trilogy" of TBT cases: U.S.-Clove Cigarettes, U.S.-Tuna Labelling, and U.S.-COOL. This paper argues that the U.S. critique regarding the relationship between the TBT Article 2.1 and the GATT Article III is not valid. However, the critique relating to the "legitimate regulatory distinction" test (in the context of U.S.-COOL) presents interesting issues on the specific role of the TBT Agreement (in contrast to the GATT) in the trade rules. Accordingly, the paper revisits the "legitimate regulatory distinction" test newly introduced by the Appellate Body in the TBT trilogy cases.