Buried deep in the EU - Palm Oil report (paras. 7.911-7.915, on page 250!) is a nugget on developing country status in the WTO. Malaysia asserts, in the TBT context, that it is a developing Member. It cites as support that: (a) according to the World Economic Situation and Prospects (WESP) dataset, it is considered to be a developing economy; (b) UNCTAD lists it as a developing country; (c) its status as a developing country has never been contested in the framework of the WTO; and (d) in the framework of the WTO Trade Policy Review, reference is made to Malaysia as a developing country. The EU does not dispute Malaysia's status, and the Panel concludes that this evidence is "more than sufficient" to demonstrate that Malaysia is a developing country Member.
Leaving aside the accuracy of the assertion that Malaysia's status has never been contested in the WTO context -- the US for example does not treat Malaysia as a developing country for purposes of CVD de minimis rules, which implement a WTO obligation -- it is notable that Malaysia does not assert self-designation as a basis for its developing country status, nor does the Panel ever suggest that this status is self-judging or non-justiciable.
