Over its 20 years of practice, the Appellate Body gradually established a de facto stare decisis rule similar to that exists in common law system. Given the tight time constraint as provided in the DSU for an appeal process, the Appellate Body may face a situation where there is no sufficient time available for it to consider thoroughly all the elements for the interpretation of a provision, especially arguments or evidence of law that have not been raised even by the parties nor by the panel. If the issue whether Article XX of GATT 1994 can be invoked by China to justify a violation of paragraph 11.3 of its Accession Protocol had been decided in China-Raw Materials, can this issue be reopened and assessed again in China-Rare Earths? The author explored these two cases in light of the relevant WTO precedents as well as the common law thinking. This article concludes that it is both necessary and technically feasible to correct certain previous interpretation. Such a correction will contribute to further improvement in the clarification and interpretation of the covered agreements and accession protocols; hence give more confidence to Members that their rights and obligations under the treaty can be well preserved by a system with a built-in self-correction mechanism.