Means-Ends Analysis (MEA) is an essential stage of human rights cases in constitutional review. Traditionally, this analysis is conducted under formalistic notion; nevertheless, under the influence of legal realism movement, the U.S. Supreme Court had adopted interdisciplinary approaches in many cases. In recent years, the Taiwanese Constitutional Court (TCC) also shows an interest in interdisciplinary approaches occasionally. This essay will focus on some landmark human rights cases under these two jurisdictions. By comparative research, some common strengths as well as weaknesses of interdisciplinary approaches of MEA in constitutional reasoning may be revealed at a fundamental level of constitutional law that are beyond the boundaries of legal traditions (i.e. common law v. civil law). Those strengths and weaknesses may address the essence of interdisciplinary approaches to (constitutional) law as a distinctive legal methodology.