NUS Law pioneers use of AI chatbots, bringing realism to courtroom training

Most of us can picture a dramatic courtroom scene: a confident lawyer masterfully cross-examining a witness, every question a calculated step. Yet, few realise the years of meticulous practice required to reach such expertise. One particularly challenging aspect is cross-examination, a core legal skill that demands pointed, leading questions to gradually corner witnesses and expose contradictions.

Determined to find a better way to train students in cross-examination, NUS Law partnered the AI Centre for Educational Technologies (AICET) at NUS to develop AI chatbots capable of simulating courtroom scenarios. The ambition was clear: give every student a consistent, realistic opportunity to practise.

Their success on this front led NUS Law’s Associate Professor Mervyn Cheong ’08 and Assistant Professor Ang Si Yi, as well as Ms Ng Sook Mun from AICET, to present their work at the National Technology Enhanced Learning (NTEL) Conference 2025 on 4 July 2025. Their presentation, titled “AI Praxis: Learn, Engage, Advocate,” took place during the GenAI Breakout Forums and showcased their pioneering work on generative AI chatbots in legal education.

Just four months earlier, two such chatbots were launched as interactive learning tools for students enrolled in Trial Advocacy, representing the first time that Gen AI has been used to teach legal skills in the Faculty. With the AI chatbots, 126 students in the class engaged directly with the digital witness during lectures, guided through structured practice and peer review. The chatbot, programmed with detailed prompts covering case facts and witness personalities, maintained its character throughout, ensuring realistic and nuanced responses.

At NUS Law, where trial advocacy is taught to over 130 students annually—the largest such programme in Singapore—the challenge of teaching cross-examination skills is well known. Traditionally, students honed their skills through video critiques and small-group roleplays: the “witness” is another student, rarely able to maintain character or respond realistically. This leaves aspiring lawyers without sufficient chances to develop and refine these essential techniques. Many students end up as passive observers—engagement is uneven, and instructors struggle to gauge each student’s progress.

Now, students can practise their questioning techniques with confidence, knowing the AI witness will respond—sometimes evasively, sometimes defensively—just as a real witness might. They ask follow-up questions, chase inconsistencies, and adapt on the fly, building not just knowledge, but courtroom instincts.

The results have been striking. Over 85% of students rated the chatbot’s usefulness at four out of five or higher. Many described the AI as “realistic,” noting it didn’t spill facts too easily and forced them to sharpen their questioning sequences. One student remarked, “It helped me practise developing question sequences because I could formulate my next question based on the chatbot’s response.” Another celebrated the fact that the chatbot “knows all the hypothetical facts and can engage realistically”, removing the need to train fellow students before each practice.

Yet, challenges remain. Students must still learn to transfer their techniques to new, unfamiliar scenarios, and few continue practising outside class unless required. To address this, NUS Law is expanding the chatbot’s repertoire, simulating client interviews where students must extract information in real time—another indispensable legal skill.

This innovative “AI Praxis” model—combining technique instruction, guided practice and confidence-building—holds great promise. AI chatbots are proving not only scalable and interactive, but also invaluable in helping the next generation of lawyers develop crucial advocacy and communication skills in a safe, realistic environment.