Singapore's highest court on Friday rejected the appeal of a convicted Malaysian drug trafficker against his mandatory death sentence and said the punishment was constitutional, according to dpa. The convict's remaining hopes now lie in a clemency plea before the city-state's president. Yong Vui Kong, 22, was convicted of smuggling about 47 grams of heroin in 2007 and was given the death penalty, which in Singapore is mandatory for all crimes involving more than 15 grams of the drug. Yong's lawyer, M Ravi, challenged the constitutionality of the ruling, saying it was "cruel and inhuman" and not in line with customary international law, but the Court of Appeal dismissed his arguments. The Singapore constitution did not imply any "prohibition of inhuman punishment," said Chief Justice Chan Sek Keong, adding that there was also no "customary international law prohibiting the mandatory death penalty as inhuman." "We dismiss the appeal," the justice said. The case had attracted attention from groups opposed to the death penalty like Amnesty International, which started campaigns to save Yong's life. Yong, who did not challenge his conviction, was sentenced to death in November and was set to be executed in December. His lawyer, however, obtained a rare stay of execution days before the punishment was to be carried out. Given the chance to dispute the legitimacy of the sentence, Ravi argued in a court hearing in March that the mandatory death sentence for drug crimes was unconstitutional because it gave the judges no chance for taking into account mitigating factors like youth. In addition, the sentence infringed the right of equal protection guaranteed by Singapore's constitution, the lawyer said. "When you sentence someone for 15 grams of drugs and someone for 100 kilograms, that's a difference, and discretion should come in," Ravi argued. The prosecution, on the other hand, said the mandatory death penalty was constitutional because it was in line with laws passed by the legislature. "The Parliament sets the parameters within which the court gives sentences," Attorney General Walter Woon said, arguing that the harsh punishment was needed to protect Singapore from the harm of drugs. It was "state practices that determine international law, not the other way round," he added. The Court of Appeal on Friday accepted the prosecution's arguments, saying the court was not permitted to interfere in legislation. "The Court of Appeal considered that, under Singapore law as it stood, further challenges in court to the constitutionality of the mandatory death penalty had been foreclosed by its decision in this appeal," the court said in his ruling. After the verdict by the city-state's highest court, Yong now has the option to file a plea for clemency with President SR Nathan. It would represent a second such attempt after Nathan rejected Yong's first petition for clemency in December. But this time, the call for mercy would be even more desperate, Ravi said, because comments on Yong's case made by Singapore's law minister this week affected any coming decision. Referring to Yong's case, Minister K Shanmugam last Sunday justified Singapore's mandatory death penalty for drug traffickers, saying it would send a wrong signal if the Malaysian were spared the sentence because of his youth. "We [would be] sending a signal to all drug barons out there: Just make sure to choose a victim who is young or a mother of a young child and use them as the people to carry the drugs into Singapore," local media quoted the minister as saying. The mandatory death sentence has been critical in Singapore's effective fight against drugs, Shanmugam said, while charging that most other countries already had lost the fight. Yong's lawyer on Friday denounced Shanmugam's remarks, adding, "The whole clemency process is poisoned." "We have to challenge the minister's statement," Ravi said.