Best practices in police data retention - exploratory efforts

March 4, 2017

 At the request of a Canadian police service, I was asked whether any agency or experts had developed a set of best practices for retention of police records. The short answer is no. The next step was to develop a small exploratory study, the results of which I share below.




This report explores the best practices in data retention for police organizations. In order to maximize the potential of crime analytics, the optimal length of time that an organization should retain data for was investigated. Both police organizations and academic experts in crime analysis were contacted in order to determine if there is a consensus in data retention practices based on the following questions:


1)     How long (should a/does your) police organization keep service call data?

2)     How long (should a/does your) police organization keep occurrence reports?

3)     How long (should a/does your) police organization keep other record types?




Two groups were contacted for this report: police organizations that are recognized for doing complex crime analytic work, and internationally renowned experts who specialize in place-based criminology and crime analytics. An email including a summary of the project and the research questions were sent to 15 police organizations and 22 academics from the US, the UK, and Australia. Over the course of one month, 1 police organization and 14 experts responded.  




The police organization indicated that they kept both service call data and occurrence reports for six years if it was a standard crime (e.g., theft), and for 12 years if it was for a serious crime (e.g., homicide or a sexual crime).


All of the experts agreed that longer data retention was optimal in order to explore long-term trends and identify patterns. 


Two (n=2) of the 14 experts stated that service call data and occurrence reports should be actively accessible for five years; however, all data should be archived indefinitely. Six (n=6) experts agreed that all record types should be kept for a ‘minimum’ of 10-15 years; however, each of these individuals also felt that keeping records indefinitely would be ideal. Further, six (n=6) experts did not entertain a ‘best’ termination date to data retention, arguing that technology today is capable of unlimited data collection and storage and should therefore never be deleted.  


In short, 7 or 50% of respondents cited a period of 10-15 years as ideal, with an absolute minimum of 5 years.




It is reasonable to conclude that ideally, all data – service call data, occurrence reports, and other record types – should be retained indefinitely. However, due to resource and storage restrictions in some police departments, as well as privacy concerns regarding certain record types (e.g., data from body worn cameras on police officers), there may be requirements to establish time limits on data retention. Based on the findings, it is recommended that all record types be preserved for ten years. As more police departments adopt better technology that can manage and store greater amounts of data, retention periods will expand. Policies will have to be adjusted and/or developed for individual data types in order to account for privacy and accessibility concerns.




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