Tuesday, October 16, 2007

Sex Offender Recidivism: A Simple Question

Abstract (and PDF link)

This study examines sexual recidivism, as expressed by new charges or convictions for sexual offences, using the data from 10 follow-up studies of adult male sexual offenders (combined sample of 4,724). Results indicated that most sexual offenders do not re-offend sexually, that first-time sexual offenders are significantly less likely to sexually re-offend than those with previous sexual convictions, and that offenders over the age of 50 are less likely to re-offend than younger offenders. In addition, it was found that the longer offenders remained offence-free in the community the less likely they are to re-offend sexually. Data shows that rapists, incest offenders, “girl-victim” child molesters, and “boy-victim” child molesters recidivate at significantly different rates. These results challenge some commonly held beliefs about sexual recidivism and have implications for policies designed to manage the risk posed by convicted sexual offenders.


Just about everybody would like to know how often sexual offenders recidivate with another sexual offence. Concerned politicians, an engaged media, and worried parents often assume that the recidivism risk of sexual offenders is extremely high, and routinely ask those working with this population questions such as “all sex offenders do it again don’t they?” and “won’t they just do it again if you let them out?” Such questions are best answered by appealing to research evidence; first, however, it is important to carefully consider the question being asked.

A Simple Question

The basic question about sexual offender recidivism is usually phrased along the following lines: “what percentage of sexual offenders commit another sexual offence once they’ve been released from prison?” This question is not as easy to answer as one might believe. First, we must define “recidivism”. In some studies, recidivism is defined as a reconviction for a sexual offence (e.g., Hanson, Scott & Steffy, 1995). In other studies, recidivism includes all offenders who were charged with a new sexual offence, whether or not they were convicted (e.g., Song & Lieb, 1995). Including charges along with convictions should, of course, lead to higher estimates of recidivism (Prentky, Lee, Knight & Cerce, 1997). Other studies have used expanded definitions of sexual recidivism that include informal reports to child protection agencies, self-report, violations of conditional release conditions, and simply being questioned by police (e.g., Marshall & Barbaree, 1988). All else being equal, the estimated recidivism rate should increase with each expansion of the definition; the broader the definition, the larger the recidivism estimate should appear. Consequently, it is important to specify the recidivism criteria in any recidivism estimate (e.g., “what percentage of sexual offenders are either charged with, or convicted of, another sexual offence once they’ve been released from prison?”)

Another factor to consider is the length of the follow-up period. As the follow-up period increases, the cumulative number of recidivists can only increase. It is important to remember, however, that an increase in the number of recidivists is not the same as an increase in the yearly rate of recidivism. For all crimes (and almost all behaviours) the likelihood that the behaviour will reappear decreases the longer the person has abstained from that behaviour. The recidivism rate within the first two years after release from prison is much higher than the recidivism rate between years 10 and 12 after release from prison. Consequently, any estimate of sexual re-offending must be “time-defined” or “time limited” (e.g., “over the first five years, post-release from prison, what percentage of sexual offenders are either charged with, or convicted of, another sexual offence?”)

A third factor to consider is the diversity among sexual offenders. We know that incest offenders recidivate at a significantly lower rate than offenders who target victims outside the family (Hanson & Bussière, 1998). We also know that child molesters with male victims recidivate at a significantly higher rate than child molesters that only have girl victims (Hanson & Bussière, 1998). By considering the type of sexual offender, our simple question becomes, once again, more complex: (e.g., “over the first five years, post-release from prison, what percentage of child molesters with male victims are either charged with, or convicted of, another sexual offence?”)

Many sexual offences are never reported to police; this is the same for all violent offences except murder. Our best estimates of unreported sexual offending come from victimization studies. In a typical study a random sample of people are telephoned and asked if they have been a victim of a crime within the last year. One recent victimization study found that there were approximately half a million sexual assaults (499,000) committed in Canada in 1999 (Besserer & Trainor, 2000). Although reports to police of violent and sexual crimes were steadily declining in Canada between the years 1993 and 1999; the years 2000 and 2001 saw 1% increases in violent and sexual crimes (Savoie, 2002). Sexual victimization rates based upon victimization surveys appear to have remained basically unchanged across this same time period (Besserer & Trainor, 2000). The Besserer and Trainor (2000) study showed that sexual assault had the highest percentage of incidents that were not reported to police (78%). When respondents were asked why they did not report sexual victimization to the police, 59% of the respondents stated that the “incident was not important enough” to report. Consequently, readers may wonder what counts as a sexual assault.

The Besserer and Trainor (2000) victimization study used a very broad definition of sexual assault. They counted all attempts at forced sexual activity, all unwanted sexual touching, grabbing, kissing, and fondling, as well as threats of sexual assault (Jennifer Tuffs, personal communication, January 15, 2003). Their broad definition undoubtedly included some behaviours that do not conform to the popular image of a sexual offence.

All unwanted sexual advances are wrong, possibly criminal, and have the potential to do psychological harm to the victim. As a society, however, we need to decide whether we wish to count an unwanted touch on the buttocks as an unreported sexual crime. Coming to an agreement on what constitutes a sexual crime will be a difficult task. Setting the bar too low would criminalize social clumsiness and over-state the problem of sexual assault. Setting the bar too high would devalue those victims who, while sustaining no overt signs of trauma, may have truly suffered at the hands of a sexual assailant. A detailed examination of the relationship between observed and undetected sexual offences is beyond the scope of the current paper. Readers should be aware, however, that the answer to the simple question of sexual offence recidivism requires specifying the nature of the offences being considered. In the analyses that follow, recidivism is defined as sexual offences reported to police that are credible and sufficiently serious to justify charges or convictions.

The above review indicates that the simple question is not so simple. Rather than asking “how often do sexual offenders re-offend”; the informed reader would inquire about the recidivism rates of particular types of sexual offenders (e.g., incest offenders versus rapists for example), over a specific time period (e.g., 10 years) using a particular definition of recidivism (e.g., new convictions for a sexual offence). Failure to specify these distinctions can lead to wildly different estimates of the rate of sexual recidivism. The present study addresses the question of sexual offender recidivism using a large, diverse sample drawn from multiple jurisdictions. The combined sample is sufficiently large (4,724) that it is possible to calculate stable estimates of the observed recidivism rates after five, 10, and 15 years of follow-up for important subgroups of sexual offenders: rapists, girl victim child molesters, boy victim child molesters, incest offenders, those with or without a prior sexual offence, older offenders (age greater than 50 at release) and younger offenders. This study also provides recidivism estimates for sex offenders who have been offence-free in the community for 5, 10, and 15 years.

Key cites:

  • Results
  • Sexual recidivism was measured using the original definitions from the original research reports: 5 data sets used convictions, 4 data sets used new charges (or a new conviction), and one sample used convictions, charges, and additional police information (Manitoba). The five and 10 year recidivism estimates were 17% and 21% for the studies that used only convictions as their recidivism criteria, and 12% and 19% for the studies that used charges and convictions as their recidivism criteria. Given the similarity in the recidivism rates based on convictions alone and charges and convictions, the data was combined to provide overall estimates of sexual recidivism rates. The rates estimated using the combined sample would be closer to the reconviction rate than the re-arrest rate because it appeared that the sources used for the recidivism data contained relatively few charges that did not ultimately result in conviction.
  • Sexual recidivism rates
  • Table 2 summarises the recidivism estimates for three distinct time periods, five years, ten years, and fifteen years, for each of the subgroups examined. The overall recidivism rates (14% after 5 years, 20% after 10 years and 24% after 15 years) were similar for rapists (14%, 21% and 24%) and the combined group of child molesters (13%, 18%, and 23%). There were, however, significant differences between the child molesters, with the highest rates observed among the extrafamilial boy-victim child molesters (35% after 15 years) and the lowest observed rates for the incest offenders (13% after 15 years). Offenders with a prior sexual offence conviction had recidivism rates about double the rate observed for first-time sexual offenders (19% versus 37% after 15 years). Age also had a substantial association with recidivism, with offenders older than age 50 at release reoffending at half the rate of the younger (less than 50) offenders (12% versus 26%, respectively, after 15 years). As expected, those who have remained offence free in the community were at reduced risk for subsequent sexual recidivism. Whereas the average 10 year recidivism rate from time of release was 20%, the 10 year recidivism declined to 12% after five years offence-free and to 9% after 10 years offence-free. The five year recidivism rate for those who had been offence-free for 15 years was 4%. Offence-free was defined as no new sexual or violent non-sexual offence, and no non-violent offences serious enough that they are incarcerated at the end of the follow-up period.
  • Discussion
  • Most sexual offenders do not re-offend sexually over time. This may be the most important finding of this study as this finding is contrary to some strongly held beliefs. After 15 years, 73% of sexual offenders had not been charged with, or convicted of, another sexual offence. The sample was sufficiently large that very strong contradictory evidence is necessary to substantially change these recidivism estimates. Other studies have found similar results. Hanson and Bussière’s (1998) quantitative review of recidivism studies found an average recidivism rate of 13.4% after a follow-up period of 4-5 years (n = 23,393). In a recent U.S. study of 9,691 sex offenders, the sexual recidivism rate was only 5.3% after three years (Langan, Schmitt, & Durose, 2003).
  • Not all sexual offenders, however, were equally likely to reoffend. By using simple, easily observed characteristics, it was possible to differentiate between offenders whose five year recidivism rate was 5%, from those whose recidivism rate was 25%. The factors associated with increased risk were the following: a) male victims, b) prior sexual offences, and c) young age.
  • Although the number of recidivists increases with extended follow-up, the rate of offending decreases the longer offenders have been offence-free. The five year recidivism rate for new releases of 14% decreased to 4% for individuals who have been offence-free for 15 years. The observed rates underestimate the actual rates because not all sexual offences are detected; nevertheless, the current findings contrast with the popular notion that all sexual offender remain at risk throughout their lifespan.
  • The observed recidivism rates in the current study are slightly lower than the lifetime sexual recidivism rates estimated by Doren (1998) - 52% for child molesters and 39% for rapists. Doren’s estimates were largely based on long-term follow-up of highly selected samples (Hanson et al., 1995; Prentky, et al., 1997); in contrast, the current study used larger and more diverse samples, including many low risk offenders serving community sentences. Doren’s (1998) estimates were also based on charges, whereas most of the recidivism data in the current study was based on convictions.
  • Policy implications
    Although no finding is ever definitive, the basic findings of the current study are sufficiently reliable to have implications for criminal justice policy. Given that the level of sexual recidivism is lower than commonly believed, discussions of the risk posed by sexual offenders should clearly differentiate between the high public concern about these offences and the relatively low probability of sexual re-offence.

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