Yong Vui Kong vs. Public Prosecutor, 2010 SGCA 20 (Singapore)

The appellant Vui Kong was convicted of trafficking in diamorphine (heroin), a controlled drug, and sentenced to death. He challenged the constitutionality of the Misuse of Drugs Act (MDA) provision, under which the mandatory death penalty (MDP) is imposed, which does not allow court discretion in imposing the death penalty, given certain amounts of dangerous drugs. 

Appellant argued, among others that customary international law should be considered in the interpretation of the word "law" in Article 9(1) of the constitution which provides that "[n]o person shall be deprived of his life or personal liberty except according to procedure established by law." Thus, the imposition of the MDP as provided in the MDA is not in accordance with the law, particularly the prohibition against "cruel and inhumane punishment" under customary international law. 

The court recognized that domestic law should, as far as practicable, be interpreted consistently with international obligations. However, there are inherent limits on the extent to which the courts may refer to international human rights norms for this purpose. For instance, reference to international human right norms would not be appropriate where the expressed wording of the Singapore Constitution is not amenable to the incorporation of the international norms in question. Where the Singapore Constitution is concerned, it is not possible to incorporate a prohibition against inhumane punishment through the interpretation of existing provisions. First, the Singapore Constitution does not contain any expressed prohibition against inhumane punishment. Second, it is not possible to interpret the Singapore Constitution as incorporating a prohibition against inhumane punishment because a proposal to add an expressed constitutional provision to this effect was made to the Government in 1966 by the constitutional commission but that proposal was ultimately rejected.