Proactive policing can be described as preventing crime, while reactive policing involves responding to a crime that is taking place right now or that has already taken place.
A great example of proactive policing would be police patrolling a section of an interstate where drivers are known for driving fast or recklessly. If this were done regularly then motorists would become accustomed to the possibility of police being there, and this possibility is likely to deter them from driving recklessly.
Reactive policing, on the other hand, involves reacting to something that has already happened. For example, if the police go to someone's house after they have called 911 and stated that a robbery is taking place, then they are reacting to a crime that has already taken place.
Both types of policing are imperative to the effective functioning of society. Proactive policing has a preventative role, while reactive policing is responsible for obtaining justice during or after criminal activity.
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