The expected costs of releasing sex offenders

An interesting post on a very contentious topic over at The Commons caught my eye. Author Jonathan McLeod weighs into the debate over whether we should change how we pardon sex offenders in Canada. He argues we should use hard numbers rather than emotions to make these decisions. Although like many Canadians I have strong emotions on this topic, the economist in me tends to agree with McLeod.

McLeod then describes some data he found, which suggests that sex offenders are less likely to re-offend than the average criminal. Thus, he concludes that "statistics demand that we offer no special punishment to sex offenders seeking pardons."

But after looking into this a little deeper, I think the data shows the opposite: releasing sex offenders poses more of a cost to society than the average criminal.

The key flaw in McLeod's analysis is that by looking only at the chance of re-offending, he is assuming that all crimes are created equal. This, I believe, is a very unreasonable assumption.

To do a proper analysis, one would need to obtain three pieces of information. First, we would need to know how likely it is that a sex offender re-offends compared with the average criminal. McLeod obtains this number from a Canadian Department of Justice report: 12.4% of sex offenders re-offend, compared with 30.1% of general criminals.

Second, we need to know whether sex offenders who re-offend commit different types of offences than general criminals who re-offend. Intuitively, one might expect sex offenders to be more likely to commit another sex crime than a general criminal. It turns out this is true. A study by the U.S. Department of Justice found that 5.3% of sex offenders were re-arrested for a sex crime within three years of being released from prison, compared with 1.3% of general criminals.

Third, we need to know whether all crimes are in fact created equal, as McLeod assumes. As economists, this means we probably want to attach a monetary cost to different types of crime. But coming up with the cost of a crime can be difficult. If someone steals my watch, there is the obvious cost of replacing my watch. But when word of the crime gets around, others will experience a psychological cost whereby they start looking over their shoulders in case the watch thief sneaks up on them. How do we calculate the cost this? And what about the security guards that watch stores must now employ to ensure no more watches get stolen?

Calculating the costs of crimes is not my area of expertise. But poking around online, it is clear that some people have attempted to do this. I found a 2000 study by the U.K. government that calculates the costs of various types of crime. They find that the cost of the average crime is £2,000. Not surprisingly, their cost estimate of the average sex offence is much higher: £19,000. Their estimates are based mostly on direct effects of crime. They do not take into account costs to the victim's quality of life, prevention costs, or costs of people fearing potential crimes. My guess is that this would cause the cost of the average sex offence to be underestimated relative to the average crime.

Putting the three pieces of data together (the chance of re-offending, the chance of re-offending with a sex offence, and the cost of sex offences relative to other crimes), we can then compare how releasing a sex offender compares with releasing an ordinary offender.

Let's assume a sex offender has a 12.4% chance of re-offending, and that they have a 5.3% chance of re-offending with a sex crime (obviously, one number comes from Canada and one from the U.S. Also, the first number presumably has no time frame on it, whereas the second number has a three-year time frame. But it's better than nothing). Putting these numbers together, we can assume that a sex offender will have a 5.3% chance of committing another sex crime, and a 7.1% chance (12.4 - 5.3 = 7.1) of committing a general crime.

We can multiply these probabilities by the cost of the two types of crime to see what the expected cost of releasing a sex offender is. The calculation is (0.053 x £19,000) + (0.071 x £2,000) = £1,149.

Now we can repeat for general criminals. They have a 1.3% chance of re-offending with a sex crime, and a 28.8% chance of re-offending with a general crime. That works out to an expected release cost of £823.

My method is by no means flawless. But these back-of-the-envelope calculations suggest that it is, on average, 40% costlier to society to release a sex offender than it is to release a general criminal. It appears the push to make it tougher for sex offenders to obtain a pardon is in fact supported by data.