Background <p>Traditional policing interventions associated with the standard model of policing, such as programmes designed to arrest and prosecute repeat offenders, have not been effective in controlling crime. In contrast, a growing number of rigorous programme evaluations find focused deterrence strategies, designed to change offender behaviour through a blended law enforcement, social service and opportunity provision, and community-based action approach, are effective in controlling crime. While evidence is growing, there are few randomised controlled trials evaluating this type of intervention, particularly assessing the effect on repeat serious violence offenders.</p> Methods <p>The police force will identify individuals involved in 3 or more serious violence offenses, with the most recent serious violence offense occurring within the last 24&#xa0;months in the recorded crime data. Eligible individuals are placed within one of six strata based on gender and age group. Within each stratum, 50% of individuals are randomly allocated to the treatment condition and the rest to the control condition. All participants will receive usual care, but those randomly assigned to the experimental condition will receive a focused deterrence intervention visit from police providing a scripted empathetic talk and a list of local resources. The police will collect crime data for all individuals for the 12&#xa0;months following the date of randomisation. The primary outcome is the total crime harm, measured by the Cambridge Crime Harm Index, perpetrated by the individual across all crimes committed in the year following randomisation (across England and Wales). The secondary outcomes include the number of arrests for violent crime, the total number of arrests, the number of non-violent arrests, and the time to the first arrest within the same timeframe.</p> Discussion <p>Current RCTs investigating FD interventions focus on crime counts, but this assumes parity amongst crimes. Our study will assess the impact on both crime harm and crime counts to provide a comprehensive review of the impact of this intervention. If the hypotheses are supported, this single-contact FD intervention would likely have significant operational appeal for police and communities to prevent and reduce crime and harm with light-touch engagement.</p> Trial registration <p>The study is now listed on the ISRCTN registry with study registration number ISRCTN35233331. Registered on&#xa0;24 July 2024.</p>