Arrest data biases predictive tools because police are known to arrest more people in Black and other minority neighborhoods, which leads algorithms to direct more policing to those areas, which leads to more arrests. The result is that predictive tools misallocate police patrols: some neighborhoods are unfairly designated crime hot spots while others are underpoliced.

Call for more transparency on how such tools are used in public services as 20 councils stop using computer algorithms. The Home Office recently stopped using an algorithm to help decide visa applications after allegations that it contained “entrenched racism”.