Criminology Expert Witness

Overview

About Criminology Expert Witnesses

A criminology expert decides what crime data and research can honestly say about a place, a population or a risk: how likely a crime was at this property, what the numbers mean, and how far group findings can be carried to one person. The work is social science applied to a specific question. This page covers crime patterns, foreseeability and recidivism research. A negligent security expert addresses what a property should have done about the risk, a police procedures expert addresses department conduct, and a forensic psychologist addresses one individual's mental state and risk.

The expert reads police calls for service, incident reports, property security logs, census and land use data, published studies and any prior crime history at the site. Calls for service and reported offenses are different records, and they tell different stories, so the first task is often sorting out what each one counts.

Foreseeability and the Place

In a negligent security case, the usual question is whether the crime was foreseeable at this location, under the forum's test. Courts use different tests, so counsel should tell the expert which applies before work begins. The criminologist's job is to build the crime picture for the right place and time: how big an area, how many years, which offenses and how similar they are to the event at issue.

Those choices drive the answer. A one-mile radius in a dense city and a one-block radius can give opposite impressions. Counting every call to an address includes false alarms and minor disputes. An opposing expert will press on whether the prior incidents were similar enough, and near enough, to give notice.

Official counts also understate crime. The National Crime Victimization Survey exists in part for that reason: it collects crimes both reported and not reported to the police, and asks whether each crime was reported and why or why not ¹. It samples about 240,000 persons in about 150,000 households each year ¹. It gives national context, but it cannot describe a single parking lot, so the expert has to say what it adds and where it stops.

Recidivism Research

Recidivism comes up in sentencing, parole, civil commitment and negligent hiring. The National Institute of Justice describes it as a person's relapse into criminal behavior, and says it is often measured by rearrest, reconviction or return to incarceration during a specific follow-up period ². Definitions matter a great deal. A rate measured by rearrest at three years is a different number from one measured by reconviction at one year.

Time matters as well. NIJ reports a Bureau of Justice Statistics study of state prisoners released in 2005: an estimated 68 percent were arrested within 3 years, 79 percent within 6 years and 83 percent within 9 years ³. It also notes that forty-four percent were arrested during the first year ³. Those are group figures for one release cohort, measured by arrest, and an arrest is not a conviction. NIJ cautions that criminologists may not have a valid way of measuring whether a crime has occurred ³.

The largest limit is moving from groups to individuals. A rate says how often something happened among many people. It does not say what this person will do. A careful report keeps that distinction in view, and states who was in the study, what outcome was measured and how the person at issue differs.

Deterrence and Policy

Criminologists also testify about what prevents crime. NIJ says the certainty of being caught is a vastly more powerful deterrent than the punishment, and that increasing the severity of punishment does little to deter crime ⁴. Those findings can support testimony on mitigation, on the value of visible guardians, and on why a property's patrols might have mattered. They are general findings and do not prove what would have happened at one location on one night, which is the causation question in most security cases.

Rule 702 applies to this work like any other. An expert must show the opinion rests on sufficient facts and a reliable application of the method, and each opinion must stay within those bounds ⁵. Research should be cited for what it found, and the fit to these facts should be explained and not assumed.

Who Is Qualified

Look for a doctorate in criminology, criminal justice, sociology or a related field, with published work on the specific subject: place-based crime, recidivism, or risk. No license exists. Ask whether the expert has worked directly with police records, not only published datasets. Former police analysts can help on data, and a negligent security expert or forensic psychologist may be needed for the steps that follow.

Qualifications

Qualifications to Look For

• ✓Doctorate in criminology, criminal justice, sociology or a related field
• ✓Published research on the specific subject: place-based crime, recidivism or risk
• ✓Direct work with police records, calls for service and crime mapping
• ✓Clear explanation of what group data can and cannot say about one person
• ✓No license exists, so the research record is the credential
• ✓Experience stating sampling frames, follow-up periods and outcome measures
• ✓Prior deposition or trial testimony that survived a reliability challenge

FAQ

Frequently Asked Questions