Sui Yi Siong

Yi Siong has expertise in criminal litigation at both the trial and appellate level, having appeared as lead counsel at all levels of the Singapore courts including the Court of Appeal. As defence counsel, he has represented clients across the entire spectrum of white-collar and blue-collar offences, ranging from market manipulation and money laundering offences to religiously aggravated assault and maid abuse. In Public Prosecutor v Bong Sim Swan Suzanna [2020] 2 SLR 1001, he defended a Prosecution criminal reference to the Court of Appeal that is now the locus classicus on whether an accused's knowledge arising from uncharged prior offending conduct can be considered in sentencing.

Yi Siong taps on his criminal law experience to advise and act for institutional clients in matters relating to professional discipline and quasi-criminal work. He regularly advises the Institute of Singapore Chartered Accountants on disciplinary cases, and has been instructed to act as prosecuting counsel for the Singapore Medical Council, Singapore Dental Council and other healthcare professional boards, as well as statutory bodies like the Energy Market Authority.

Apart from his criminal law practice, Yi Siong also a general disputes practice, handling a broad range of civil matters including medical negligence, employment law, and deputyship applications under the Mental Capacity Act. He was instrumental in updating the 2025 edition of Halsbury's Laws of Singapore on Medical Negligence and Professional Misconduct, having previously contributed to Halsbury's Laws of Singapore on Civil Procedure.

• Acted as co-counsel for the 2nd accused in Singapore's longest criminal trial which state prosecutors called the most serious case of stock market manipulation in Singapore; in the course of trial, acted as lead counsel in various important applications that raised novel questions of criminal law, such as the applicability of litigation privilege over communications between prosecutors and investigators (Public Prosecutor v Soh Chee Wen [2020] 3 SLR 1435) and whether criminal proceedings can be stayed for abuse of process (Public Prosecutor v Soh Chee Wen [2021] 3 SLR 641)
• Advised a Singapore Exchange mainboard listed company on the potential liability of its former managing director who was charged for conspiring to cheat a government body by concealing discounts with its subcontractor over a 3 year period
• Acting for a Malaysian alleged to be part of a regional syndicate operating an Android OS malware-enabled scam responsible for millions of dollars of losses from Singaporeans