The two men, who were arrested for smuggling drugs into the country, would be the first executions carried out by the island-state since November of 2019, if their sentence is upheld.
Singapore's High Court heard the challenge to the sentence of hanging in the morning, a day after the Court of Appeal rejected an application to review and halt the execution set for Wednesday, said N. Surendran, a member of the Lawyers for Liberty group in Malaysia.
"We are waiting for the court's decision," he said, describing the execution as unconstitutional.
Malaysian Pausi Jefridin and Singaporean Roslan Bakar were sentenced to death in 2010, two years after being arrested. Lawyers and rights activists say Pausi has an IQ of only 67 — a level that is internationally recognised as an intellectual disability — while Roslan has a borderline range of intellectual functioning.
In 2017, a lower court judge found that the duo had "displayed competence and comprehension" while carrying out the act they were sentenced for, according to the Transformative Justice Collective, an anti-death penalty movement in Singapore.
The case resembles that of Malaysian national Nagaenthran K. Dharmalingam, whose scheduled hanging last November sparked widespread anger as he is believed to be mentally disabled with an IQ of 69. His appeal to the top court was postponed after he was diagnosed with COVID-19, and is due to he heard in March.
"Following more than two years of no executions in 2020 and 2021, it is appalling that the Singapore government is planning to resume this cruel practice imminently," Amnesty International's Singapore researcher Rachel Chhoa-Howard said in a statement.
The death-row cases have also put the spotlight on Singapore's capital punishment for drug-related offences.
Ravina Shamdasani, a spokesperson for the UN High Commissioner for Human Rights, said the death penalty can only be imposed for the "most serious crimes", which is interpreted as crimes of extreme gravity involving intentional killing.
"We call on the Government to commute their sentences, and to reform Singapore's legislation to bring an end to the imposition of the death penalty," she said.