The Home Office – the main UK public authority responsible for immigration – is keenly interested in identifying ‘sham’ marriages which are designed to game the immigration system. Since at least 2015, the department has used an automated system to determine whether to investigate a proposed marriage. Marriage registrars across the country transmit details of proposed marriages to the system via ‘data feeds’. The system applies eight ‘risk factors’ to assess the risk that a couple's marriage is a sham. These risk factors include the couple's interactions before the registrar, ‘shared travel events’, and age difference. The system allocates couples either a ‘green’ rating, indicating that no investigation is warranted, or a ‘red’ rating, indicating that an investigation is warranted to identify possible ‘sham activity’. This algorithm processes a large number of marriages each year. In a 12- month period across 2019 and 2020, the Home Office received 16,600 notifications of marriages involving a non- European national, of which 1,299 were subsequently investigated. These investigations can have a range of adverse consequences for individuals and their families, and they inevitably reach into the most private aspects of people's lives in a manner that can be ‘gruelling’. There have been recent reports of wedding ceremonies being interrupted so that officials can question people about their sex lives, an official finding a nude photograph on a person's phone and showing it to others in the room, and dawn raids being carried out to check if couples are sharing a bed. We know little about how this automated system works, its impacts on those processed by it, and how effective it has been in successfully detecting sham marriages. This example of automation's growing role in government immigration systems is not unique. In fact, it is being replicated in many different corners of the Home Office immigration bureaucracy. The Home Office is currently one of the largest purchasers of IT services in government. The government's 2025 border strategy promises a ‘border ecosystem’ where ‘[a] ccurate data is gathered efficiently and shared across government at scale’, thereby ‘maximising data driven, automated decision making’.