The key issue here is a familiar one: the alleged unauthorised use of data to train an AI model. If Microsoft or OpenAI used Twitter data without proper authorisation or payment, it could potentially be seen as a violation of Twitter’s terms of service, or even a breach of privacy laws. This case highlights several novel legal problems posed by the use of AI. 

Firstly, AI models require large amounts of data for training. The source and usage of this data can raise legal issues, particularly if the data is processed without proper authorisation or payment. Secondly, the use of publicly available data, such as tweets, to train AI models can potentially raise privacy concerns. Even though the data is public, its use for purposes other than intended could potentially be seen as a breach of privacy. As AI technology advances and becomes more integrated into various industries, determining responsibility for the actions of AI models becomes increasingly complex. In this case, the relationship between Microsoft and OpenAI adds an additional layer of complexity to the issue of responsibility.