This Paper explores balancing test on issues of human life and health used by WTO panel and the Appellate Body. This paper compared two cases between Brazilian Case and US Case which the Appellate Body endorsed a balancing approach in deciding whether a measure in question is “necessary” in GATT Art XX (b). Through the report in Brazilian Case, the Appellate Body provided important and controversial views regarding the interpretation of “necessary” of GATT Art XX (b). The balancing test, used to determine Art XX (b) necessity in Brazilian Case, serves as a useful solution such as how the WTO should address the problem moving toward. By making the chapeau analysis part of balancing test, it would give the WTO flexibility and could stepped toward harmonization between trade and environment.