develop skills or change one's psychological make-up to reduce the likelihood of future offences). In recent decades in many countries in the world, the criminal justice system has taken an increasing interest in preventing violence before it occurs. For instance, much of community and problem-oriented policing aims to reduce crime and violence by altering the conditions that foster it—and not to increase the number of arrests. Indeed, some police leaders have gone so far as to say the police should primarily be a crime prevention agency. Juvenile justice systems—an important component of criminal justice systems—are largely based on the belief in rehabilitation and prevention. In the US, the criminal justice system has, for instance, funded school- and community-based initiatives to reduce children's access to guns and teach conflict resolution. Despite this, force is used routinely against juveniles by police. In 1974, the US Department of Justice assumed primary responsibility for delinquency prevention programmes and created the Office of Juvenile Justice and Delinquency Prevention, which has supported the "Blueprints for violence prevention" programme at the University of Colorado Boulder. Public health The public health approach is a science-driven, population-based, interdisciplinary, intersectoral approach based on the ecological model which emphasizes primary prevention. Rather than focusing on individuals, the public health approach aims to provide the maximum benefit for the largest number of people, and to extend better care and safety to entire populations. The public health approach is interdisciplinary, drawing upon knowledge from many disciplines including medicine, epidemiology, sociology, psychology, criminology, education and economics. Because all forms of violence are multi-faceted problems, the public health approach emphasizes a multi-sectoral response. It has been proved time and again that cooperative efforts from such diverse sectors as health, education, social welfare, and criminal justice are often necessary to solve what are usually assumed to be purely "criminal" or "medical" problems. The public health approach considers that violence, rather than being the result of any single factor, is the outcome of multiple risk factors and causes, interacting at four levels of a nested hierarchy (individual, close relationship/family, community and wider society) of the Social ecological model. From a public health perspective, prevention strategies can be classified into three types: Primary prevention – approaches that aim to prevent violence before it occurs. Secondary prevention – approaches that focus on the more immediate responses to violence, such as pre-hospital care, emergency services or treatment for sexually transmitted