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Working as a maxillofacial surgeon in Glasgow in the early 2000s, Christine Goodall treated hundreds, if not thousands, of patients with injuries to the neck, face, head and jaw.

Once, a young man came into the hospital in the middle of the night with a knife wound across his face. Goodall dreaded telling him that it would be impossible to reduce the appearance of the scar. But his reaction surprised her. “He was very offhand about it,” she says. “Some of his friends came to see him later that afternoon and I realised why it wasn’t going to be a problem for him – because they all had one. He’d just joined the club.”

The incident has stayed with her as an indication of how bad the situation in her city had become.

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In 2005, the United Nations published a report declaring Scotland the most violent country in the developed world. The same year, a study by the World Health Organization (WHO) of crime figures in 21 European countries showed that Glasgow was the ‘murder capital’ of Europe. More than 1,000 people a year required treatment for facial trauma alone. “We were really good at patching injuries up,” says Goodall. “But I started to think: what can we do to prevent them coming here in the first place?” 

A woman shows the knife she carries with her in Glasgow in 2005, the year the city was named Europe’s most violent (Credit: Getty Images)

Humans engage in a wide array of risky behaviours that can lead to serious health problems: smoking, overeating, sex without protection. It has long been the accepted wisdom that doctors should encourage patients to change their behaviour – give up smoking, go on a diet, use a condom – rather than wait to treat the emphysema, obesity-related heart attacks, or HIV that could result.

But when it comes to violence, the discussion is often underpinned by an assumption that this is an innate and immutable behaviour and that people engaging in it are beyond redemption. More often than not, solutions have been sought in the criminal justice system, such as through tougher sentencing.

Since the Violence Reduction Unit launched, Glasgow’s murder rate has dropped by 60%

Enforcement alone, however, often does not work. In 2005, Karyn McCluskey, principal analyst for Strathclyde Police, wrote a report pointing out that traditional policing was not actually reducing violent crime. In search of a different approach, McCluskey’s team, led by her and her colleague John Carnochan, began pulling together evidence on the drivers of violence. “Particularly in Scotland, it was poverty, inequality, things like toxic masculinity, alcohol use, all these factors – most of which were outside the bounds of policing,” says Will Linden, who worked for McCluskey as an analyst at the time. Next, the team looked around the world to find and learn from pioneering programmes working to prevent violence.

This was the foundation of the Violence Reduction Unit (VRU), of which Linden is now the acting director. Since the VRU was launched in 2005, the murder rate in Glasgow has dropped by 60%. The number of facial trauma patients passing through Glasgow’s hospitals has halved, Goodall says, and now stands at around 500 a year.

The VRU’s strategy is described as a “public health” approach to preventing violence. This refers to a whole school of thought that suggests that violent behaviour itself is an epidemic that spreads from person to person.

One of the primary indicators that someone will carry out an act of violence is their first being the victim of one

One of the primary indicators that someone will carry out an act of violence is being a victim of one beforehand. The idea that violence spreads between people, reproducing itself and shifting group norms, explains why one area might see fewer stabbings or shootings than another – even if it has many of the same social problems.

Photos and shoes of gun violence victims are exhibited at an anti-gun rally in Philadelphia in 2018 (Credit: Getty Images)

“Despite the fact that violence has always been present, the world does not have to accept it as an inevitable part of the human condition,” says the WHO guidance on violence prevention. “Violence can be prevented and its impact reduced, in the same way that public health efforts have prevented and reduced pregnancy-related complications, workplace injuries, infectious diseases, and illness resulting from contaminated food and water in many parts of the world.”

But across much of the world, being ‘tough on crime’ is a vote winner, which makes this a hard sell. How did Glasgow do it? As they investigated what it actually means to treat violence as a health problem, the VRU looked first to Chicago.


In the 1980s and early 1990s, US epidemiologist Gary Slutkin was in Somalia, one of six doctors working across 40 refugee camps containing a million people. His focus was on containing the spread of tuberculosis (TB) and cholera.

Containing infectious diseases relies heavily on data. First, public health officials map out exactly where the most transmissions of the disease are occurring. Then they can focus on containing the spread in these areas. Often, this containment happens by getting people to change their behaviour so that a rapid effect can be seen even when larger structural factors can’t be tackled.

For instance, diarrhoeal disease is often in large part caused by poor sanitation and water supplies. It takes a long time to improve plumbing systems. But in the meantime, thousands of lives can be saved by giving people oral rehydration solutions.

Long-term solutions are needed to fight epidemics, but quicker fixes – like oral rehydration salts – can save lives in the meantime (Credit: Getty Images)

Slutkin followed these steps to contain outbreaks in the Somali refugee camps, and again later, when he worked for the WHO on Aids prevention. Whatever the exact nature of the infectious disease in question, the steps to contain it were roughly the same.

“What do they have in common? All of these things spread,” Slutkin says. “Heart disease doesn’t spread, strokes don’t spread.”

Changing behavioural norms is far more effective than simply giving people information. To change behaviour – whether it’s using rehydration solutions, avoiding dirty water or using condoms – credible messengers are essential. “In all of these outbreaks we used outreach workers from the same group” as the target population, says Slutkin. “Refugees in Somalia to reach refugees with TB or cholera, sex workers to reach sex workers with Aids, moms to reach moms on breastfeeding and diarrhoeal management.”

Girls wash their hands at their school’s facilities in Malawi – one example of how people’s behaviour can be changed to save lives (Credit: Getty Images)

After more than a decade working overseas, Slutkin returned to his native Chicago in the late 1990s. “I wanted a break from all these epidemics,” he says. But he returned to a different kind of problem: a skyrocketing homicide rate.

Flu causes more flu, colds cause more colds, and violence causes more violence – Gary Slutkin

Wanting to tackle this, too, he gathered maps and data on gun violence in Chicago. As he did so, the parallels with the maps of disease outbreaks he was accustomed to were unavoidable. “The epidemic curves are the same, the clustering. In fact, one event leads to another, which is diagnostic of a contagious process. Flu causes more flu, colds cause more colds, and violence causes more violence.”

This was a radical departure from mainstream thinking about violence at the time, which primarily focused on enforcement. The popular idea was “that these people are ‘bad’ and we know what to do with them – which is punish them,” says Slutkin. “That’s fundamentally a misunderstanding of the human. Behaviour is formed by modelling and copying.”

Jesse Jackson stands with Rose Braxton at a 2009 rally in South Side, Chicago; Braxton’s 16-year-old nephew was beaten to death in a brawl (Credit: Getty Images)

Chicago is deeply racially segregated. Many South Side neighbourhoods are over 95% African-American; others are more than 95% Mexican-American. Most of these areas are severely socioeconomically deprived and have suffered years of state neglect. Homicide rates can be up to 10 times higher than in more affluent, predominantly white areas.

But Slutkin emphasises that this clustering is less to do with race and more to do with patterns of behaviour – usually among a small section of the population, usually young and male – that are transmitted between people. He argued that lives could be saved by changing the behaviour of individuals and shifting group norms.

In 2000, he launched a pilot project in the West Garfield neighbourhood of Chicago. It replicated the same steps as the WHO takes to control outbreaks of cholera, TB or HIV: interrupt transmission, prevent future spread, and change group norms.

Within the first year, there was a 67% drop in homicides

Within the first year, there was a 67% drop in homicides. More neighbourhoods were piloted. Everywhere it launched, homicides dropped by at least 40%. The approach began to be replicated in other cities.

Today, Slutkin’s organisation Cure Violence works in 13 Chicago neighbourhoods. Versions of the programme run in New York, Baltimore and Los Angeles and other countries around the world.

Although there is a level of debate about Cure Violence’s use of statistics, the method’s overall effectiveness has been shown by numerous academic studies. A 2009 study at Northwestern University found that crime went down in all neighbourhoods examined where the programme was active. In 2012, researchers at Johns Hopkins School of Public Health looked at four parts of Baltimore that were running the programme, and found that shootings and homicides fell in all four.

Violent crime rates are among the world's highest in San Pedro Sula, Honduras, but violence fell in areas where Cure Violence’s approach was implemented (Credit: Getty Images)

The results are frequently striking. In San Pedro Sula, Honduras, the first five Cure Violence zones saw a drop from 98 shootings during January-May 2014 to just 12 in the same period in 2015.


Demetrius Cole is 43, a gentle, softly-spoken man who spent 12 years in prison. He grew up in an area of Chicago afflicted by violence and, at the age of 15, saw his best friend die in a shooting. Nonetheless, he had a stable home life and stayed out of gangs. He planned to join the Marines. When he was 19, a close friend bought a new car. Some other boys from the neighbourhood tried to steal the car, and they shot Cole’s friend. Cole didn’t stop to think. He retaliated. In those few minutes, his life changed entirely. While his friend was left paralysed, unable to work again, Cole was sent to prison for his response.

I tell them, there’s only two ways this thing is going to end. You’re going to go to jail or you’re going to die – Demetrius Cole

Since October 2017, he has been working for Cure Violence in West Englewood, a South Side district of Chicago. He finds people in the same situation he was once in, and tries to persuade them to pause. “We try to show them this is a dead end. I tell them, there’s only two ways this thing is going to end. You’re going to go to jail or you’re going to die.”

Cole works as a “violence interrupter”, employed by Cure Violence to intervene in the aftermath of a shooting to prevent retaliations and to calm people down before a dispute escalates to violence. Violence interrupters use numerous techniques, some borrowed from cognitive behavioural therapy: “constructive shadowing”, which means echoing people’s words back to them; “babysitting”, which is simply staying with someone until they have cooled down; and emphasising consequences. Interrupters’ ability to be effective depends on their credibility. Many, like Cole, have served long prison sentences and can speak from experience. Most also have a close relationship with the local community.

A fight breaks out outside of a Chicago high school in 2009; Cure Violence’s approach involves calming people down before the conflict escalates to violence (Credit: Getty Images)

Although it must always be adapted for each location, Cure Violence follows roughly the same steps when establishing itself in a new place. First, map the violence to see where it clusters. Next, hire credible workers with a local connection. These interrupters patrol the streets on their beat, getting to know shopkeepers, neighbours – and building links with the young men and women deemed to be the highest risk.

The centre employs 11 interrupters, who typically spend at least six of the eight hours in a shift out in their neighbourhoods, as well as four outreach workers, who interact with participants on a more long-term basis. Over a period of six months to two years, outreach workers try to change attitudes to violence. They also connect people with job opportunities, counselling or education.

While Slutkin emphasises how quickly this model can reduce homicides, and how it costs less than mass incarceration, there is no escaping the fact that it takes a lot of workers to get results. Some of Chicago’s gang territories are very small – just a few blocks. A violence interrupter respected in one area may be unknown, or even mistrusted, in another. To work, there must be at least one interrupter with strong connections in each district, like Cole.

‘It’s hard coming back from prison and back into society’ (Credit: Getty Images)

“I’ve been there. It’s hard coming back from prison and back into society,” says Cole. “If people know of you and know your history, you’re able to stop a lot of things when it comes to shootings and killings. I’m able to show people: you can do this, you can change.”


While establishing the VRU in 2005, Karyn McCluskey and John Carnochan of Strathclyde Police searched the world for possible solutions to Glasgow’s problem with violence. What they eventually came up with blended together Gary Slutkin’s approach with that of David Kennedy, a Boston-based criminologist.

Kennedy’s model, which launched in Boston in the 1990s, entails gathering together gang members and giving them an option: renounce violence and get into education or work, or face tough penalties. This meant ramping up traditional penal measures – increased stop-and-search and stricter sentencing for knife possession – alongside preventive measures in line with the public health approach. Will Linden, the acting director of the VRU, argues that this was politically necessary. “Before we went to services to get them to do things differently, we had to show that the police were doing the best we could but it still wasn’t enough,” he says.

Scotland has the world’s only police force to have formally adopted a public health model

The VRU is run by the police force with support from the Scottish government. This is highly unusual – Scotland has the world’s only police force to have formally adopted a public health model. Cure Violence in Chicago operates through the university, while similar programmes in New York and Baltimore are administered through the cities’ health departments. But alongside police, a whole range of public officials – from doctors to social workers – are involved.

In Glasgow, meanwhile, surgeon Christine Goodall decided she had to do something. In 2008, with two other surgeons, she founded a charity called Medics Against Violence. The charity, which became a partner of the VRU, goes into schools to educate children about knife crime and to get them to think practically about how to respond if, for instance, a friend told them they had a knife.

Knife attack survivor Samar Haroun shows the scars that remain on the back of her neck in 2013 (Credit: Getty Images)

It also employs “navigators” who, like Chicago’s violence interrupters, intervene directly after violent incidents to defuse tension and help people find support. Glasgow’s navigators are not assigned to specific localities; instead, they work in accident and emergency departments and approach people who come in after a violent incident. “A lot of people come into A&E plotting revenge and it’s very important that they leave not doing that,” says Goodall.

In the violence prevention industry, this is referred to as a “reachable, teachable moment”, when someone is more receptive than usual to help. “Pain is an incredible motivator for change,” says Linden. After an initial conversation, the navigator follows up by helping the person get drug or alcohol treatment, job opportunities or therapy. They try to move quickly. “When someone wants to change, you have to be able to adapt and move,” says Linden. “In six or 12 weeks, they’ll be in a different mindset. We make sure if we refer someone, they’re not in a queue.” This requires significant cooperation between different agencies.

To see a serious effect, this work needs massive levels of collaboration – and longer than a four- or five-year election cycle. Linden notes that Scotland has an unusual level of political consensus, with successive governments funding this work.

“Just calling violence a disease and saying we need to interrupt the flow isn’t going to stop it,” he says. “Call it the public health approach, call it prevention – it doesn’t matter a damn if you don’t actually use evidence-based approaches to address the real problem.”

The difficulty is not how to reduce violence, it is the way people understand the problem

Despite the ever-growing bank of evidence, governments are sometimes reluctant to properly invest. “The difficulty is not how to reduce violence, it is the way people understand the problem,” Slutkin tells me, his frustration visible. He draws a parallel to Aids and the stigma attached to those who contracted it during the first outbreaks in the 1980s.

On a sunny evening in downtown Chicago, I watch Slutkin speak to an audience of young professionals. In Chicago, homicides reached a 20-year high in 2017 and President Donald Trump threatened to send in “the feds”.

Slutkin presents graphs showing that every time Cure Violence’s funding is cut in a certain area, shootings spike. When it returns, they drop. (Critics argue that it is impossible to draw conclusions about causality due to other factors at play.) “Despite massive amounts of data, it’s hard to get funding for this,” Slutkin tells the audience.

‘Mass imprisonment has no good data,’ says Gary Slutkin (Credit: Getty Images)

“Mass imprisonment has no good data – but it’s funded. This is the only epidemic health problem not being tackled by the health department.”


Thirteen years after it was established, the VRU has retained its flexibility and openness to new ideas. In 2012, Iain Murray, a policeman working for the VRU, travelled to Los Angeles to visit Homeboy Industries, a catering company that employs former gang members. In addition to providing employment for a year for former violent offenders, Homeboy Industries gives mentoring, psychotherapy and other support. Murray came back inspired.

The result is Braveheart Industries, a social enterprise run by the VRU. Its main business is Street and Arrow: a food truck that sits in the Partick area of Glasgow, dishing up peri-peri chicken burgers and fish tacos. It hires former violent offenders for a year, and provides intensive mentoring from a navigator as well as regular psychotherapy and assistance with literacy, housing, parenting or anything else that is required. Participants must have a criminal history, they must abstain from drugs and alcohol, and they must be ready to change.

I’d much rather be top of the cliff putting a fence up, stopping somebody jumping over, as at the bottom of the cliff waiting until they’ve jumped – Iain Murray

“We’ve got to understand what the problems are,” says Murray. “The police for years have been experts at detection and enforcement. I’d much rather be top of the cliff putting a fence up, stopping somebody jumping over, as at the bottom of the cliff waiting until they’ve jumped. That’s the public health approach as far as I’m concerned. You’re engineering out issues, rather than waiting for them to happen.”

A woman holds a poster at an anti-violence rally on Chicago’s South Side

Allen, 27, has been working at Street and Arrow for three months. When I ask how long he had spent in prison, he isn’t able to tell me: he’s lost track. According to Murray, he’s been sent to prison 27 times. “I didn’t come from a supportive background, so I chose the wrong path – drink, drugs, violence, chaos, prison,” says Allen, a tall, well-built man who avoids eye contact. “That was my life. It’s hard to escape once you start.”

After his last prison stint, he went into rehab. Someone there told him about Street and Arrow. He applied for a job, and was shocked when he got it. “I came up here with nothing, and I mean nothing,” he tells me. “But the more I was away from the chaos, the more my life just got better and better.”

I just want a peaceful life. I never wanted that before – Allen

He pauses, trying to think of a way to express the changes. “I see people with cars now and I just… that’s not something I ever thought about doing. Now I’ve got plans to start my driving licence. I just want a peaceful life,” he says. “I never wanted that before, I just wanted to take drugs.”

For many participants, apparently simple things can be a challenge: arriving on time, taking orders, wearing a uniform. The navigators support them through this so that at the end of a year, they’re prepared for a normal job. At the same time, there are echoes of Chicago’s interrupters, modifying behaviour to prevent the transmission of violence. The navigators build a relationship with trainees and help them change their responses to conflict.

The programme has been highly successful, with 80% of participants staying out of prison and going on to other employment. Murray has noticed the drastic difference in Allen. “I know from my previous roles in policing over the years, I could have arrested that guy 10 times in a row and I wouldn’t have made a blind bit of difference to his behaviour. By supporting him and connecting with him, I can make a long-term, sustainable change to his behaviour,” he says.

“I cannot believe how good that guy is. I cannot get him to leave work. It’s remarkable to see. You start caring about them and they start caring about themselves.”

This is an edited version of an article first published by Wellcome on Mosaic and is republished here under a Creative Commons licence. Sign up to the newsletter at www.mosaicscience.com/#newsletter.

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