In recent years, the United Kingdom's Home Office has started using automated systems to make immigration decisions. These systems promise faster, more accurate, and cheaper decision-making, but in practice they have exposed people to distress, disruption, and even deportation. This book identifies a pattern of risky experimentation with automated systems in the Home Office. It analyses three recent case studies including: a voice recognition system used to detect fraud in English-language testing; an algorithm for identifying 'risky' visa applications; and automated decision-making in the EU Settlement Scheme. The book argues that a precautionary approach is essential to ensure that society benefits from government automation without exposing individuals to unacceptable risks.