Deterrence 101

Park patrols, baggage checks at customs, market vendor raids, confiscations, fines, sentencing…  What do these enforcement actions all have in common? They are all examples of things that could result in deterrence. But when we talk about deterrence what do we actually mean?

Deterrence is referred to as the inhibition of criminal behaviour by fear especially of punishment, and is the goal of a dominant crime prevention strategy that is deeply embedded in criminal justice systems and everyday life. The law may state that you can receive a ticket if you are speeding, or that someone will go to jail if they commit a violent crime. We even use it for children who are told that if they don’t smarten up they won't get to watch Saturday morning cartoons on TV. The punishment can be as varied as the violation, but the goal is always to prevent someone from breaking a rule through a threat of sanction.

So deterrence strategies are commonplace. BUT do they work? To answer this question, criminologists have broken down deterrence into constituent parts that can be measured.

The Concept of Deterrence

The concept of deterrence dates back to the foundations of criminology in the 18th century. Specifically, two philosophers, Cesare Beccaria and Jeremy Bentham called for changes to the criminal justice system that would include fair legal process and clearly defined laws (Beccaria, 1764/2009; Bentham, 1789).  They stated that punishment should not be excessive and should only be punitive to the point of crime prevention.  As part of this, punishment was defined as having three elements of deterrence: certainty, swiftness, and severity.  

Today the three core elements of deterrence are still measured by criminologists.

  1. Certainty - the chances of being caught doing something you’re not supposed to be doing.  

  2. Severity - how severely you will be punished if you are caught.

  3. Swiftness - (also referred to as celerity) how quickly you will receive a punishment.

Collectively, these concepts allow us to state a basic theory of deterrence:  If a punishment is perceived as sufficiently certain, severe and swift, people will abstain or desist from criminal activity.  

To illustrate, let’s consider speeding and the reasons why I may choose not to press harder on that gas pedal because of the deterrent effect of traffic police (even if I’m late for a meeting):

  1. They have speed traps everywhere, so I think there is a high chance I’m going to get caught (certainty).

  2. The fine for speeding is really high and will cost me hundreds of dollars (and I’m broke) (severity).

  3. I’m going to have to pay a fine right away, so I will feel the burn immediately (swiftness).  

In summary, deterrence theory predicts that if you fear being caught and receiving a severe sanction you will be deterred and drive at, or below, the speed limit. In addition, a swift punishment will be more painful - much like you punish a child now versus later so they associate the punishment with the act.

Other Dimensions of Deterrence

Beyond the core concept of deterrence, some criminologists also conceptualize deterrence as influencing a person generally or specifically.  

In the case of general deterrence, a person perceives punishment to be sufficiently swift, severe and certain for a crime and chooses not to ever participate in it.  For example, I heard that there were a lot of speed checks on the road, so I won't speed. Or, a friend got a big fine for speeding, and I don’t want the same thing to happen to me. Basically, general deterrence is the fear of a perceived punishment experienced by those who have not been punished in the past.

Meanwhile, specific deterrence is when a person has been caught, punished and does not wish to repeat the experience so they do not commit another crime.  For example, I got a huge speeding ticket last week and I don’t want it to happen again, so now I’m driving at tortoise speed.

Deterrence & Wildlife Crime

Now let’s put this into a wildlife crime context. The deterrence elements for a poacher may be the threat of being caught by rangers (certainty), a lengthy jail sentence if caught (severity) and an immediate arrest or court date (swiftness). For a wildlife trafficker moving exotic pets across the border, there is the risk that a border officer will discover the box of parrots (certainty), that there will be a $20,000 fine (severity), and that they will have to pay the fine of the spot (swiftness).

The core idea of deterrence theory is that a poacher or trafficker will weigh the probability of these things occurring and make a decision based on the potential deterrence costs and the benefits of continuing the illegal activity. They will not participate in the activity if they perceive the severity, certainty, and swiftness to be sufficiently high, whether this is something that they have heard will happen (general deterrence) or it is something they have experienced in the past (specific deterrence).  

Does Deterrence Work?

All this conceptualizing brings us back to our earlier question: does deterrence work?

The literature on deterrence is extensive, covering a range of crimes from murder to speeding to violent crime to drug use. Some research found deterrent effects and others found no deterrent effects. Nagin (2013) summarized the combined results from multiple studies and found more consistent evidence of support for certainty of punishment than for severity. That is, the perceived certainty of being caught doing something you’re not supposed to be doing is more often associated with a deterrent effect than the perceived severity of the punishment.

However, it is rare that all of the elements of deterrence are tested at the same time (Nagin, 2013). Most tests of deterrence look at certainty of being caught and severity of punishment, but swiftness of punishment is rarely tested (Nagin, 2013) (mainly because it is difficult). Further, research has shown that deterrence is nuanced, for example, different types of people can be deterred differently (Nagin 2013). Or that the relationship between certainty (likelihood of being caught) and deterrence are not necessarily linear - i.e., a one unit increase in the certainty of being caught does not necessarily equal a one unit increase in deterrence (Loughran et al., 2012). In summary, deterrence works in some situations and not others; it can deter some people, but not all; more enforcement effort will not necessarily result in more deterrence; and there is more support for certainty as a deterrent than for severity and celerity.

Deterring Wildlife Crime

Deterrence does not always work the way it was intended.  Without considering the role of certainty, severity or swiftness, it is difficult to determine the effectiveness of sanctions, or how they will impact offender or general public perceptions. This is especially true when parks use rangers for anti-poaching programs, or governments consider raising fines or prison sentences. If these tools are not effective or are overly punitive, then we need to change strategies. However, we can only tell if they are effective deterrents by measuring the specific elements. A few studies have done this in the wildlife crime context (e.g., in fisheries compliance, Kuperan & Sutinen, 1998) but to-date there have been very few tests of deterrence in the environmental context, particularly with regard to wildlife trafficking. Moving forward, organizations working on wildlife crime may benefit from collaboration with criminologists to establish methods to measure and evaluate the deterrent effect of their programs.


For more on deterrence in the wildlife crime context see:

Moreto, W. D., & Gau, J. M. (2017). Deterrence, legitimacy and wildlife crime in protected areas. In M.L. Gore (Ed.). Conservation Criminology (45-60). Chichester, UK: Wiley-Blackwell.



  • Beccaria, C. (1764/2009). On crimes and punishments. Seven Treasures Publications.
  • Bentham, J. (1789). An introduction to the principles of morals and legislation. New York, NY; Hafner. Open-Access Link
  • Kuperan, K., & Sutinen, J. G. (1998). Blue water crime: Deterrence, legitimacy, and compliance in fisheries. Law & Society Review, 32(2), 309–337. Closed-Access Link
  • Loughran, T. A., Pogarsky, G., Piquero, A. R., & Paternoster, R. (2012). Re-examining the functional form of the certainty effect in deterrence theory. Justice Quarterly, 29(5), 712-741. Closed-Access Link
  • Nagin, D. S. (2013)  Deterrence in the twenty-first century.  Crime and Justice, 42(1), 199-263. Closed-Access Link

Header Photo Credit: Rachel Boratto