Tan Hai Peng Micheal and another (as the executors of the estate of Tan Thuan Teck, deceased) v Tan Cheong Joo and another and other matters

The executors of the estate of the late Tan Thuan Teck sued four brothers and their company, Fong Tat Holding Co Pte Ltd, in HC/OC 381/2023, HC/OC 382/2023 and HC/OC 201/2024 to recover sums outstanding on loans made by the deceased. The suits were informally consolidated and tried together over six days, and in an earlier judgment, Tan Hai Peng Micheal v Tan Cheong Joo [2025] SGHC 217, the court gave the executors judgment. This later judgment dealt with costs.

In the defendants' closing submissions, their counsel on record, Mr Goh Peck San, cited two authorities that did not exist. For one, the case name and the neutral citation each belonged to a real case but not to each other; the other was wholly invented, and neither supported the propositions advanced. The claimants' counsel discovered this. Mr Goh had engaged another solicitor, Mr Amarjit Singh Sidhu, to research and draft the submissions, and Mr Sidhu said a paralegal who had since left his firm prepared the first draft. Neither could say whether an AI tool was used. Both apologised, accepted that personal costs orders should be made against them, proposed $1,500 jointly, and asked for the matter to be dealt with privately.

1. Whether a personal costs order could be made against a solicitor who was not counsel on record
2. Whether the citation of the fictitious authorities warranted personal costs orders against the two solicitors under the three-stage test in Ridehalgh v Horsefield
3. What the quantum of the personal costs orders and of the costs of the three suits should be

The judge held that a personal costs order may be made against any solicitor responsible for costs being incurred unreasonably, so Mr Sidhu could be ordered to pay even though he was not on the record, and the court in any event has inherent power over its officers. Given the public interest, the matter could not be settled privately.

Applying the three stages, the conduct was improper as well as negligent. Using generative AI is not itself objectionable, but lawyers bear ultimate responsibility for verifying every authority placed before the court, whatever tool produced it. Mr Goh signed and filed the submissions and had a non-delegable duty to check them, and the absence of the two cases from the bundle of authorities was an obvious warning sign. Mr Sidhu read the draft twice without noticing, relied on an unsupervised paralegal and wrongly suggested that real authorities for the same points existed. Neither could explain whether an AI tool had been used, showing lax control. The fictitious cases went to the central question of who bore the burden of proving that the deceased was an excluded moneylender, so the claimants incurred real and unnecessary costs and the potential harm was serious. Deterrence and compensation made orders against each solicitor individually just.

The agreed $1,500 was plainly inadequate, and the $800 in Tajudin bin Gulam Rasul v Suriaya bte Haja Mohideen [2025] 5 SLR 518 was no benchmark because that case concerned a peripheral issue in a smaller matter. On the suits, the claimants' per-suit approach overstated costs because the issues were legally identical and not complex, with the same teams and documents, while the defendants' figures were too low.

The court ordered Mr Goh and Mr Sidhu each to pay the claimants $5,000 personally, on an indemnity basis, and refused to let the matter be resolved privately or to let Mr Sidhu bear Mr Goh's share. Costs of the suits were fixed at a global sum of $180,000 excluding disbursements, $60,000 per suit, inclusive of the personal costs, so the defendants pay $170,000. Mr Goh was directed to inform the defendants and give them a copy of the judgment, and neither solicitor may charge them for the issue.