Dr den Heyer has been asked by Police Scotland and the Scottish Institute of Policing to survey officers in response to a 22 per cent rise in assaults on police in Scotland in the past five years.

Last year, between April and June, there were 20 reported assaults on police officers each day in Scotland, among 17,000 officers.

In New Zealand, in 2019, there were 1360 “physical and non-physical” assaults against police. In 2020, that figure rose to 1518, an average of about four a day. By the end of May this year, 260 had been recorded.

Dr den Heyer says the figures in both countries are probably misleading because of under-reporting or categorisation.

In Scotland, he says, authorities don’t fully understand why assaults have risen there, but they are also interested in the wider effect on policing.

“The impact of assaults on the health and wellbeing of officers and their families is of concern and it is important that officers, and their families, receive support to help them recover as quickly as possible.”

He says there is surprisingly little academic work on the subject and very little knowledge and understanding of the factors that lead to assaults on police.

There is plenty of data and research on police use of force but not much on assaults on police. In fact, he says, there have only been two full studies that have gone into depth on the subject, and one of those was done by him in the late 1990s. The other was completed in England in 2020.

Dr den Heyer will also be looking into the motivation for assaults on police. “People often say it is social factors, unemployment or emotional or drug issues, but there is no real substantiation for that.”

In response to these gaps in the research, Dr den Heyer, who is employed by the School of Criminology and Criminal Justice at Arizona State University, says he will be reviewing assaults on police, analysing police data from Britain, Australia and New Zealand, and talking to individual officers.

He will also explore the extent to which police officers perceive that being assaulted is “part of the job” and consider ways to raise awareness among officers about the value of reporting incidents.

“The purpose of this survey and research is to build on existing evidence to explore promising practices to prevent assaults, including approaches to prevention and training and development, and to explore the drivers of assaults.”

The data gathering phase of his research includes an electronic survey and interviews with officers and other staff.

In 2020, Dr den Heyer, in conjunction with the Police Association, conducted a significant health and wellbeing survey among 4489 Police Association members, focusing on trauma and the effects of post-traumatic stress.

The results, which showed “a high prevalence” of signs of post-traumatic stress injury among serving and former officers, highlighted the need for collaboration between the association and Police on how best to respond to cases of PTS among staff.

In his role as an instructor and contributor to various academic institutions in the United States and Britain, Dr den Heyer, a former New Zealand police officer, has previously researched policing of riots, the use of Tasers and the policing of minority communities, including the use of iwi liaison officers in New Zealand.