'The Great American Car Crime Decline': School of Law academic publishes major study on the drop in US car crime levels

Professor Graham Farrell explains why car theft in the US declined by 80% between 1990 and 2020.

Professor Graham Farrell’s study 'The great American car crime decline' was published open access in Security Journal.

The study overcomes the methodological limitations of previous studies to be the first to unequivocally show that vehicle electronic engine immobilizers reduced vehicle theft in the United States by 80 percent over a 30-year period.

It included a quasi-experiment using car industry data (from the US Department of Transportation) of over 140,000 vehicle thefts to assess the effect of electronic immobilizers. It compared a 'treatment group' of vehicles fitted with electronic immobilizers at manufacture, to a matched control group.

It explains why the decline has been gradual; only about 10 percent of cars are replaced each year, so each new iteration of improved immobilizers took years to bed-in.

It concludes that the electronic engine immobilizer may be the most important crime prevention device of modern times. This is the first study to comprehensively demonstrate the role of security in declining crime in the United States.

Professor Farrell says:

I'm very happy to see this study published, not just because it has taken me many years, but because it is a big piece in the overall jigsaw puzzle of the international crime drop. This means that, fingers crossed, it makes a big contribution to the understanding of how to prevent crime and criminality generally.

He has shared his research through articles with Dr Toby Davies in The Conversation: on public misconceptions about the crime drop and, most recently, on why stopping knife crime needs to start in the kitchen.

He is a member of the Centre for Criminal Justice Studies.