The Alcohol Abstinence Monitoring Requirement (AAMR) allows courts to impose a requirement that an individual abstains from alcohol for a fixed period and be regularly tested via a transdermal alcohol monitoring device in the form of a ‘tag’ fitted around the ankle. Inspired by a similar approach from South Dakota, USA, the AAMR formed a key strand of the Mayor’s Office for Policing and Crime (MOPAC) approach to tackling and reducing alcohol-related crime in London. This chapter explores the work of the, at the time, newly formed Evidence and Insight (E&I) team to evaluate the AAMR—the first compulsory sobriety scheme in Europe—from a 2014 initial proof of concept pilot, a 2016 London-wide scale-up, to informing the national 2021 rollout. Evaluation results were positive with high compliance and the technology working as intended, although the impact on reoffending presented a more mixed picture. However, learning went beyond performance metrics and into the importance of dedicated project management and transparent, realistic dialogue and expectation management regarding the scale and nature of evaluation. The chapter reflects on the legacy of this in terms of productive and collaborative working relationships between the E&I team and MOPAC policy colleagues.