（三）措施是否構成對國際貿易的變相限製
在“美國精煉汽油和傳統汽油標準案”中，上訴機構認為，“對國際貿易的變相限製”需要與“武斷或不正當的歧視”結合起來理解：‘Arbitrary discrimination’, ‘unjustifiable discrimination’ and ‘disguised restriction’ on international trade may, accordingly, be read side-by-side; they impart meaning to one another. It is clear to us that ‘disguised restriction’ includes disguised discrimination in international trade. It is equally clear that concealed or unannounced restriction or discrimination in international trade does not exhaust the meaning of ‘disguised restriction.’ We consider that ‘disguised restriction’, whatever else it covers, may properly be read as embracing restrictions amounting to arbitrary or unjustifiable discrimination in international trade taken under the guise of a measure formally within the terms of an exception listed in Article ⅩⅩ. Put in a somewhat different manner, the kinds of considerations pertinent in deciding whether the application of a particular measure amounts to ‘arbitrary or unjustifiable discrimination’, may also be taken into account in determining the presence of a ‘disguised restriction’ on international trade. The fundamental theme is to be found in the purpose and object of avoiding abuse or illegitimate use of the exceptions to substantive rules available in Article ⅩⅩ.[12]
綜上所述，根據WTO專家組和上訴機構的解釋，第20條在實踐中的適用應該分兩步走：第一步確定具體措施是否符合本條（a）到（j）項的要求，如果符合，則進行第二個步驟——確定具體措施是否符合第20條前言的附加條件。由此可見，成員方想要通過援引第20條來免除所采取的措施與WTO協議不符的責任是十分困難的，這一點在WTO爭端解決機製實踐中也有著充分地反映。
Case Study