Overview
- The trial at Lewes Crown Court ended after the complainant, anonymised as C, disclosed chat logs showing she used an AI chatbot to draft answers about the night, consent, physical evidence and her behaviour afterward.
- R’s defence argued those logs made it impossible to tell which parts of C’s testimony came from her memory and which came from the AI, a point the court found undermined a fair trial.
- The Court of Appeal held that private use of AI in this way can amount to 'witness coaching', which is banned in UK criminal trials, and it said courts should discourage witnesses from using chatbots when preparing evidence.
- The judges ordered a retrial at the earliest opportunity and explained that AI could unintentionally reshape an honest witness’s memory or let a dishonest witness ‘improve’ testimony.
- The ruling raises wider questions for prosecutors and judges about new rules and safeguards for witness preparation, including how courts will treat commonplace tools such as ChatGPT, Claude or Gemini going forward.