simple majority of all the MPs present and voting, the supermajority requirement is more rigorous and gives the Constitution its rigid characteristic. However, the present ruling party, the People's Action Party ("PAP") has commanded a majority of more than two-thirds of the seats in Parliament since 1968. In addition, due to the presence of the party whip, all PAP MPs must vote in accordance with the party line save where the whip is lifted, usually for matters of conscience. Thus, in substance the more stringent amendment requirement has not imposed any real limitation on Parliament's ability to amend the Constitution. One reason for having a special constitutional amendment procedure is because constitutional supremacy requires the Constitution to endure in the long term with its main principles largely unchanged. However, in Singapore, this concept has been undermined by numerous major constitutional amendments made after 1979. These amendments, which significantly altered the structure and nature of the government in Singapore, introduced the Group Representation Constituency and Elected President scheme, and inducted NCMPs and NMPs into Parliament. Judicial review Dicey's third legal criterion for constitutional supremacy is the existence of an authority to pronounce upon the legal validity or constitutionality of laws passed by the nation's law-making body. While the Constitution does not expressly vest powers of constitutional judicial review in the courts, this role has been assumed by the judiciary. Hence, the third criterion appears to be fulfilled. However, the judiciary has used its power to adjudge executive actions and Acts of Parliament unconstitutional and void rather sparingly. To date, the only instance where the High Court struck down a statutory provision was in Taw Cheng Kong v. Public Prosecutor (1998). It was short-lived, as the decision was later overturned by the Court of Appeal. Delivering the Court's judgment, Chief Justice Yong Pung How emphasized the limits of judicial review, stating that it is not for the courts to dictate the scope and ambit of a section or rule on its propriety. This is a matter which only Parliament can decide, and the courts can only interpret what is enacted. This results in a conflict between the court's responsibility to be faithful to the Constitution, and its apparently restricted role in reviewing legislation. As mentioned earlier, the High Court also held that in judicially reviewing legislation, there should be a strong presumption of constitutional validity. The burden of proof falls on the