Case Details
- Citation: [2026] SGHC 49
- Title: 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
- Court: High Court of the Republic of Singapore (General Division)
- Date of Judgment: 6 March 2026
- Originating Claims: Originating Claim Nos 381 of 2023, 382 of 2023 and 201 of 2024
- Judges: S Mohan J
- Hearing Dates: 10, 18 September, 18 November, 3, 9, 15 December 2025
- Parties (Claimants/Applicants): Tan Hai Peng Micheal and another (as the executors of the estate of Tan Thuan Teck, deceased)
- Parties (Defendants/Respondents): Tan Cheong Joo and another and other matters
- Other Defendants (as reflected in O.C. 201/2024): Tan Siong Tiew, Tan Siong Lim, Fong Tat Holding Co Pte Ltd
- Legal Areas: Civil Procedure — Costs; Civil Procedure — Costs — Artificial intelligence; Citation of fictitious authority; Personal costs order against solicitor
- Statutes Referenced: Legal Profession Act 1966
- Prior Related Decision: Tan Hai Peng Micheal v Tan Cheong Joo [2025] SGHC 217 (“First Judgment”)
- Judgment Length: 40 pages, 11,760 words
Summary
This High Court decision, delivered by S Mohan J, is a sequel to the court’s earlier merits judgment in Tan Hai Peng Micheal v Tan Cheong Joo [2025] SGHC 217. While the First Judgment determined liability and granted judgment to the executors of the deceased’s estate in the underlying loan recovery suits, the present decision focuses on costs consequences arising from a serious procedural and ethical breach: the citation of fictitious authorities in the defendants’ closing submissions. The court treated the issue as one that required careful, structured analysis because it implicated the integrity of court proceedings and the professional responsibilities of advocates and solicitors when using generative artificial intelligence (“GenAI”).
The court found that the defendants’ counsel, Mr Goh Peck San, had cited two “fictitious authorities” (referred to in the judgment as “Case A” and “Case B”) in paragraphs 67 and 68 of the closing submissions. The court further examined whether the solicitor who assisted with research, Mr Amarjit Singh Sidhu, could also be personally ordered to compensate the claimants for the unnecessary costs caused by the misconduct. Applying a staged framework, the court concluded that personal costs orders were justified in the circumstances, and it emphasised that the use of AI does not dilute an advocate’s duty to verify accuracy and to ensure that citations are real and relevant.
What Were the Facts of This Case?
The underlying dispute concerned several loans made by the late Tan Thuan Teck (“TTT”) to the defendants. The defendants comprised four brothers—Tan Cheong Joo, Tan Seong Kok, Tan Siong Tiew, and Tan Siong Lim—and a company, Fong Tat Holding Co Pte Ltd, in which the brothers were directors and/or shareholders. The claimants were TTT’s sons, who were also the co-executors of his estate. They commenced three actions to recover sums allegedly still outstanding under the loans: HC/OC 381/2023, HC/OC 382/2023, and HC/OC 201/2024. The suits were informally consolidated for trial.
In the First Judgment, the court held that the defendants failed to establish their defences and that the claimants’ case was made out. Judgment was therefore granted to the claimants in the suits. However, the present decision does not revisit the merits. Instead, it addresses what happened in the defendants’ closing submissions after the trial, specifically the citation of authorities that were later discovered to be fictitious.
Central to the costs inquiry was the “Fictitious Authorities Issue”. In the defendants’ closing submissions, counsel for the defendants, Mr Goh, cited two “cases” in paragraphs 67 and 68. Although the neutral citation and the case name for Case A appeared to correspond individually to real cases, the neutral citation belonged to a different case altogether; when the neutral citation was combined with the case name, the resulting “Case A” did not exist. As for Case B, both the case name and neutral citation were entirely fictitious. Moreover, neither authority supported the legal propositions for which they were cited.
The claimants’ counsel detected the problem and raised it in reply submissions. The court then investigated. Mr Goh acknowledged that the fictitious authorities had been provided by another solicitor he had engaged to assist with research and drafting—Mr Sidhu. Mr Goh expressed regret and indicated he was unaware which AI tool, if any, had been used. The court required further clarification, including identification of the assisting solicitor and the steps taken to verify the accuracy and existence of the cited authorities. Mr Sidhu explained that the initial research and draft were prepared by an unnamed paralegal who had since left the firm, and that Mr Sidhu had reviewed and transmitted the materials to Mr Goh. Mr Sidhu conceded he had overlooked the fictitious authorities and had failed to appreciate that Case A and Case B were not on point or could not be located on LawNet. The court also required information about verification steps and whether AI tools were used.
What Were the Key Legal Issues?
The primary legal issue was whether the citation of fictitious authorities in closing submissions warranted a personal costs order against the defendants’ solicitors, rather than merely an order as between parties. The court had to consider whether the conduct of Mr Goh and/or Mr Sidhu amounted to acting improperly, unreasonably, or negligently in a manner that caused the claimants to incur unnecessary costs.
A second, related issue was the scope of responsibility. Even if the fictitious authorities were initially supplied by an assisting solicitor or paralegal, the court needed to determine whether the solicitor on record (Mr Goh) and the assisting solicitor (Mr Sidhu) could both be held personally liable for the resulting costs. This required the court to consider the professional chain of responsibility in litigation: who must verify citations, what steps are expected, and how far personal costs orders should extend.
Finally, the court had to decide the appropriate quantum and extent of costs to be compensated. This included whether the personal costs order should cover the whole or only part of the relevant costs, and whether it was just in all the circumstances to order the solicitors to bear their share of personal costs.
How Did the Court Analyse the Issues?
The court adopted a structured approach, reflecting the seriousness of personal costs orders and the need for principled reasoning. It proceeded in stages. In Stage 1, the court asked whether Mr Goh and/or Mr Sidhu acted improperly, unreasonably, or negligently. The court’s analysis was anchored in the fact that fictitious authorities were cited in closing submissions—an act that directly undermines the accuracy and reliability of submissions to the court. The court treated the issue as one that goes beyond mere oversight, because citations are fundamental to legal argument and the court’s ability to evaluate submissions.
In Stage 2, the court considered causation: whether the solicitors’ conduct caused the claimants to incur unnecessary costs. Here, the court focused on the procedural consequences of the fictitious citations. The claimants had to identify the problem, highlight it in reply submissions, and prompt the court to investigate. The court’s own directions and requests for further information also generated additional procedural steps. The court therefore examined whether the costs incurred were attributable to the misconduct or negligence in failing to verify the authorities before filing and relying on them in closing submissions.
In Stage 3, the court assessed whether, in all the circumstances, it was just to order the solicitors to compensate the claimants for the whole or any part of the relevant costs. This stage required balancing factors such as the nature of the breach, the degree of responsibility, the presence or absence of remorse, and the extent to which the solicitors’ conduct departed from expected professional standards. The court’s reasoning reflects a broader judicial concern: that the integrity of court proceedings must be protected, and that the legal profession must evolve its practices when using GenAI, without lowering verification standards.
Although the judgment is framed around costs, the court’s analysis is explicitly connected to GenAI misuse. The court noted that there were reasonable grounds to suspect that the fictitious citations were likely generated by an AI tool. However, the court did not treat AI generation as an excuse. Instead, it emphasised that advocates and solicitors remain responsible for what they file and cite. The court’s approach effectively underscores that even where AI is involved, verification duties remain non-delegable: counsel must ensure that authorities exist, are correctly cited, and support the propositions advanced. The court also considered the internal workflow described by Mr Sidhu—research by a paralegal, review by him, and transmission to Mr Goh—and found that the failure to detect the fictitious citations reflected inadequate checking and insufficient safeguards.
What Was the Outcome?
The court ordered costs consequences arising from the fictitious authorities issue. In particular, it made personal costs orders against the relevant solicitors, reflecting that the misconduct was not merely a technical error but a breach that caused unnecessary costs and required court intervention. The practical effect is that the claimants were able to recover specified costs from the solicitors personally, rather than being limited to recovery from the opposing parties.
The judgment also addressed whether Mr Sidhu should be permitted to bear only Mr Goh’s share of personal costs. The court’s conclusion, based on the staged framework and the evidence of responsibility and causation, indicates that both the solicitor on record and the assisting solicitor could be implicated where their conduct fell below professional standards and where their actions contributed to the unnecessary costs incurred by the claimants.
Why Does This Case Matter?
This case is significant for practitioners because it clarifies that personal costs orders can be imposed where fictitious authorities are cited, particularly in the context of AI-assisted research. The decision signals that courts will treat such conduct as a serious threat to the integrity of litigation. For lawyers, the message is clear: the use of GenAI does not reduce the duty to verify. Counsel must implement robust internal checks to ensure that any AI-generated citations are real, correctly cited, and relevant to the legal propositions being advanced.
From a precedent perspective, the judgment builds on the First Judgment’s findings and develops the costs jurisprudence around fictitious citations. It demonstrates that courts will not confine the response to an order as between parties. Instead, where the conduct is sufficiently improper, unreasonable, or negligent—and where it causes unnecessary costs—personal costs orders may follow. This is particularly relevant for firms that outsource research tasks internally or rely on junior staff or paralegals to process AI outputs, because the court’s reasoning indicates that verification cannot be treated as someone else’s responsibility.
For law students and litigators, the decision is also useful as a template for understanding how courts structure costs reasoning. The staged framework—improper/unreasonable/negligent conduct, causation of unnecessary costs, and whether it is just to order compensation—provides a disciplined method for analysing personal costs. Practitioners can use this framework when assessing litigation risk, advising clients, and developing compliance procedures for AI use in drafting and research.
Legislation Referenced
- Legal Profession Act 1966
Cases Cited
- [2025] SGHC 214
- [2025] SGHC 217
- [2026] SGHC 16
- [2026] SGHC 49
Source Documents
This article analyses [2026] SGHC 49 for legal research and educational purposes. It does not constitute legal advice. Readers should consult the full judgment for the Court's complete reasoning.