Even though accountability is a necessary goal and assigning responsibilities to a specific processor is absolutely necessary, controllers must always be conscious that AI functioning can make it extremely difficult to monitor a system. As the CNIL stated, “the question of where accountability and decision-making can be set up is to be approached in a slightly different way when dealing with machine learning systems”. Therefore, controllers should better think more in terms of a chain of accountability, from the system designer right through to its user, via the person who will be feeding the training data into this system. The latter will operate differently depending on such input data.

On this subject, one could mention Microsoft’s chatbot Tay. It was shut down a mere twenty-four hours after its release when, learning from the posts of social media users, it had begun to tweet racist and sexist comments of its own. Needless to say, working out the precise share of responsibility between these different links in the chain might be a laborious task.^[1]