Generative artificial intelligence ("AI") has rapidly transformed various industries, including the legal profession. Several legal AI models such as Harvey, CoCounsel, Gemini, and Latch have now been released. These tools have optimized research, drafting, and document review. While law firms were initially hesitant to adopt AI tools, their use has increasingly become standard practice. AI has proven that it can be a highly effective and useful tool in legal practice. But does that mean that lawyers can kick up their feet and relax after typing a question and hitting a button waiting for AI to revert back with an answer in seconds? If only it were so easy.
The unwritten rule remains: proceed with caution. AI is undeniably imperfect and prone to errors. In legal practice, it can hallucinate and fabricate cases and citations, posing serious risks. Recently, here in Ontario, an estate litigation hearing unexpectedly evolved into a valuable lesson for legal professionals across Canada.
The Case of Ko v Li, 2025 ONSC 2766
On May 1, 2025, during a motion concerning a deceased's estate, the Honourable Justice Myers ("Justice Myers") encountered an unusual issue.1 Counsel for the Applicant, Jisuh Lee ("Ms. Lee"), submitted a factum partially generated by AI (later confirmed to be ChatGPT).2 The factum contained citations to non-existent cases, a phenomenon known as "AI hallucinations."3
Ms. Lee failed to verify these authorities before submission and relied on them in her oral arguments. As a result, Justice Myers issued an order requiring Ms. Lee to show cause as to why she should not be cited for contempt of court.4
Duties of Lawyers in the Age of AI
In his May 1st decision, Justice Myers reiterated the fundamental responsibilities that lawyers owe to clients, the courts, and the administration of justice, outlining them as follows 5:
[16] It is the lawyer's duty to faithfully represent the law to the court.
[17] It is the lawyer's duty not to fabricate case precedents and not to mis-cite cases for propositions that they do not support.
[18] It is the lawyer's duty to use technology, conduct legal research, and prepare court documents competently.
[19] It is the lawyer's duty to supervise staff and review material prepared for her signature.
[20] It is the lawyer's duty to ensure human review of materials prepared by non-human technology such as generative artificial intelligence.
[21] It should go without saying that it is the lawyer's duty to read cases before submitting them to a court as precedential authorities. At its barest minimum, it is the lawyer's duty not to submit case authorities that do not exist or that stand for the opposite of the lawyer's submission.
[22] It is the litigation lawyer's most fundamental duty not to mislead the court.
These excerpts emphasize that the ultimate responsibility for the use of AI in the legal practice rests with the lawyer. However, in his most recent decision, Justice Myers backtracked and clarified his outlook.
Dismissal of Show Cause Proceeding in Ko v Li, ONSC 2965
On May 20, 2025, Justice Myers dismissed the show cause proceeding against Ms. Lee, despite the problematic nature of the misconduct.6 Why? Ms. Lee admitted her mistake, took responsibility, proposed corrective measures, and apologized.7 She acknowledged that her staff had used AI when drafting the factum. In a letter to the court, she undertook to complete at least six hours of CPD training on legal ethics and the responsible use of AI.8 Moreover, she amended the factum to remove all false citations.9
Justice Myers deems that the proceeding had already accomplished its objectives in addressing contempt in the face of the court.10 These objectives included:
- Maintaining the dignity of the court and the fairness of civil justice system
- Promoting honourable behaviour by counsel before the court
- Denouncing serious misconduct
- Deterring similar future misconduct by the legal profession, the public at large, and Ms. Lee specifically
- Supporting rehabilitation.
Justice Myers clarifies in this order that some of the duties he listed in his previous endorsement are not necessarily duties owed to the court 11.
[19] The Law Society of Ontario remains the regulator of licenced lawyers and paralegals in Ontario. The Law Society regulates the professional duties of lawyers in addition to their duties to the court.
Justice Myers also noted 12:
[67] In my view, the publicity surrounding this case has served both to publicly denounce inappropriate conduct and as general deterrence to the bar and others who might rely on AI for legal submissions.
[70] I think it is important to say as well, that Ms. Lee is a very senior counsel who serves Ms. Ko selflessly in the best traditions of the bar. Ms. Lee won the motion for Ms. Ko on May 1, 2025 without reliance on the factum. Ms. Lee allowed her practice standards to slip and now realizes the need to recommit to providing clients and the court with the levels of professionalism required.
Importantly, he also acknowledged a key regulatory distinction between Canada and the United States 13:
[71] In deciding not to proceed with a contempt hearing, it is possible that Ms. Lee escapes some sentencing options. In other cases where counsel have filed briefs containing fake cases from AI in the US, courts have ordered counsel to pay monetary sanctions typically in the range of US$5,000. But US courts have different roles than courts in Canada regarding the regulation of the lawyers who appear before them. They also have the ability to impose sanctions against counsel much more readily than here.
[73] There had to be someone who was going to be the first lawyer to file AI hallucinations here. It was likely to be someone so junior as to over-estimate the infallibility of AI, or someone so senior as to not really yet understand its fallibility. Ms. Lee has suffered a public shaming near the end of an unblemished career. The denunciation and deterrent effect produced her immediate and forthright response in a manner far beyond any reasonably expected impact of a small fine.
Regulatory Implications and Final Thoughts
This case raises an important question: How should regulatory bodies such as the Law Society of Ontario adapt professional conduct rules to address AI's role in legal practice?
Currently, no specific rules govern AI-related conduct in Ontario. However, the outcome in Ko v Li may serve as a precedent for future misconduct cases involving AI. For now, the legal profession must embrace innovation without compromising integrity.
AI can be a powerful tool in legal practice, but it is not a licensed lawyer. The duty to uphold the law and maintain professional integrity rests solely with the lawyer. While Ms. Lee may have been the first, she most certainly will not be the last.
Undoubtedly, senior counsel will now, when asking for articling students or young associates to draft a factum, request the supporting case law and a link to it, ensuring that neither AI or the legal professional is hallucinating, especially when arguing a position before the court!
This blog was co-authored by summer law student Aranya Sivakumar.
Footnotes
1. Ko v Li, 2025 ONSC 2766 (CanLII).
2. Ibid.
3. Ibid.
4. Ibid.
5. Ibid, at paras 16-22.
6. Ko v Li, 2025 ONSC 2965 (CanLII).
7. Ibid.
8. Ibid.
9. Ibid.
10. Ibid.
11. Ibid, at para 19.
12. Ibid, at paras 67 and 70.
13. Ibid, at paras 71 and 73.
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