Criminal Justice and People With Intellectual and Developmental Disabilities

Prevalence of Criminal Victimization of People With IDD

Data about the prevalence of people with IDD as victims/survivors of crime are fundamental to understanding the nature and extent of the issues, identifying which sub-groups of people with IDD are at greater risk, and informing prevention efforts. Recent U.S. survey and research data on prevalence are increasingly well developed. They feature age-adjusted comparisons with the general community, large and representative national samples, and improved identification of disability. IDD specifically is rarely reported in large-scale U.S. studies, which instead use broader disability groups such as cognitive disability (Harrell, 2021; Maruschak et al., 2021). Several studies from other Western countries do report IDD-specific prevalence data (Fogden et al., 2016; Ringland et al., 2022), so their findings are included below.

People With IDD From Underserved Communities Overrepresented as Victims/Survivors

Within each racial and ethnic group measured, the NCVS survey showed that U.S. people with disabilities had higher violent victimization rates than those without disabilities (Harrell, 2021). For example, Hispanics with disabilities had a victimization rate of 55.3 per 1,000 people in 2017–19, whereas the rate for Hispanics without disabilities was 12.3 (age adjusted). Among Americans with disabilities, Blacks had a lower rate of violent victimization (39.0 per 1,000) than Whites (45.1) or Hispanics (55.3; Harrell, 2021). We found no equivalent U.S. national figures on the victimization of people with IDD by race/ethnicity.

Ballan et al. (2014) undertook a retrospective file review of female survivors of intimate partner violence who used a support program for women with disabilities in New York City. Of the 886 participants, 74 (8.4%) were women with IDD. For the entire sample, only 22.4% were White and 47.6% were born outside the Unted States. Race/ethnicity data were not reported separately for women with IDD. These findings suggested that women with minoritized racial identities and/or from immigrant communities were at greater risk of interpersonal violence, but the data came from one service provider and dealt with one form of violent victimization. Much more research attention is needed to the fundamental issue of the intersection of victimization of people with IDD and underserved community status.

Prevalence of Sexual Victimization

The U.S. rate of rape or sexual assault of people with disabilities (4.1 per 1,000) was more than 4 times higher than the age-adjusted rate for those without disabilities (0.9; Harrell, 2021). Rapes or sexual assaults involving victims/survivors with disabilities (19%) were significantly less likely to be reported to police than for people without disabilities (36%; Harrell, 2021). As noted, victims/survivors with cognitive disability were the least likely to report violent crime to police (Harrell, 2021).

Information on sexual victimization of adults with ID, based on a rigorous systematic review and meta-analysis, yielded an overall prevalence of 32.9% (Tomsa et al., 2021), with a higher rate for men (39.9%) than women (31.8%). Fogden et al.’s (2016) data-linkage study found no gender differences in the rate of sexual victimization between Australian men and women with IDD, although compared to a general-community sample, the relative risk (RR) was much higher for men with IDD (RR=11.79) than women with IDD (RR=5.05). By contrast, Fisher, Corr, et al. (2016) and Khemka and Hickson (2017) cited multiple studies showing that more women were sexual abuse victims/survivors than men. These differing findings may be partly due to the setting from which data were collected. Tomsa et al.’s (2021) review found that sexual abuse is most prevalent in large institutions, especially for male victims/survivors. Male peers were the most common abusers. On the other hand, among women with IDD with intimate partners, intimate partner violence is very prevalent (Ballan et al., 2014).

Factors Associated With Sexual Victimization

Intellectual disability itself is a risk factor for victimization (Fisher, Corr, et al., 2016), and Tomsa et al. (2021) found higher prevalence among people with more severe ID. As discussed above, gender has also been found to be related to victimization risk (Khemka & Hickson, 2017; Tomsa et al., 2021). This information is useful in understanding who is at risk and in what circumstances and to help target intervention and protection efforts. However, factors such as having intellectual disability or gender cannot easily be changed. By contrast, modifiable risk factors such as knowledge/education or support can be altered and therefore are of more interest when the intention is to reduce the risk of victimization.

Consequences of Victimization

Hickson and Khemka (2021) identified four types of negative outcomes of victimization: 1) biological/physical health, 2) psychological, 3) behavioral, and 4) social. Khemka and Hickson (2017) listed a wide range of serious negative psychological issues related to domestic violence and sexual abuse of people (mostly women) with IDD. Hayes (2009) studied the outcomes of violent victimization among Australians with and without ID who were seeking victim’s compensation. People with ID were more likely to have been victims/survivors of sexual abuse and were more likely to attempt suicide. Mandell et al. (2005) found that children with autism who had been sexually abused were more likely to engage in sexual acting out, running away from home, and attempting suicide. Hickson and Khemka (2021) noted that the negative effects of victimization can continue throughout life. Making this situation worse is the reality that few therapists are skilled in both trauma and IDD, often meaning that victims/survivors with IDD have fewer therapeutic resources available to them.

Victim Compensation

All U.S. states have victim compensation programs for crimes reported to the authorities. These programs can pay for costs, including medical treatment and therapy to aid recovery. Less than 5% of victims/survivors with a disability received benefits from a victim’s program (Baladerian et al., 2013). We found no data on access to victim compensation specifically by people with IDD. This issue was not examined in recent reviews of research on criminal justice, victimization, and IDD (Cooper et al., 2022; Fisher, Corr, et al., 2016; Olley & Cox, 2021). However, the well-established lower rate of people with cognitive disability (including IDD) reporting violent victimization to police (Harrell, 2021), together with the fact that cases not reported to police (or other relevant authorities) are ineligible for victim compensation, strongly suggests that access to compensation may be particularly limited for people with IDD. Baladerian et al. (2013) proposed numerous changes to practice that could improve the situation regarding victimization of people with disabilities, including several recommendations related to victim compensation such as improved reporting, education/training, therapy, funding, and a therapy referral system. We found no data on access to victim compensation by people with IDD from underserved communities.

Anecdotal data suggest that many victims/survivors with IDD don’t know about victim compensation. Cases where people with IDD hear of victim compensation and are supported to apply often seem to arise by chance rather than through systematic information and support provision. Victims/survivors of crimes not reported to police and/or that do not proceed to court have no access to police and court victim support services that provide information on or referral to victim compensation programs, rape crisis centers, and the like. However, we know of no reliable data on these issues.

Interventions With Adults With IDD

Hickson and Khemka (2021) highlighted that maltreatment risk reduction efforts for children focus on the family home and for adolescents on school, but for adults with IDD, abuse can occur in the many different settings that this cohort accesses (home, work/day program, disability services, community). By developing self-protection skills, knowledge, and behavior, adults with IDD can potentially be empowered to reduce their risk of victimization in all settings, so it is unsurprising that this approach has been an important focus of research and intervention. Further, such approaches target characteristics of people with IDD that increase their vulnerability, namely limited social awareness (e.g., difficulty in recognizing and assessing risky social situations) and challenges with decision making in response to risk of abuse (Hickson & Khemka, 2021). Moreover, self-protection training empowers adults with IDD to manage risky situations for themselves and/or seek help, whereas protection provided by others (family, IDD service providers) too often results in disempowerment, overprotection, and/or constant supervision, with consequent reduction in freedom, independence, social inclusion, and participation.

There is a clear need for training in safety/risk reduction because research has shown that adults with IDD often do not identify appropriate, self-protective responses to realistic but hypothetical vignettes of abuse situations (Khemka & Hickson, 2017), or they fail to recognize hypothetical situations as potentially abusive (Hickson et al., 2015). In the past, self-protection training interventions have focused more on women with IDD (Dinora et al., 2021). To illustrate recent intervention efforts, their achievements, and limitations, we briefly describe 3 good quality studies that involved both male and female participants that were published in 2015 and beyond.

In a multi-site study, Dinora et al. (2021) used the 4-session classroom-based Leadership for Empowerment and Abuse Prevention (LEAP) intervention and assessed outcomes via participant verbal responses to questions about 6 video vignettes. The researchers found no significant change in correct identification of abuse situations from pre- to post-test, but there were significant improvements in the explanation of why situations were abusive and in stating what action could be taken to deal with the issue. There was no control group.

Over 8 weekly classroom meetings, Hughes et al. (2020) delivered an in-person group safety awareness training program, The Safety Class, to adult men and women with IDD. Assessment involved pre-, post-, and 3-month follow-up questionnaires. Relative to controls, intervention participants improved more on assessed knowledge of healthy relationships and abuse, safety planning, and self-efficacy. The authors noted that future research is needed on the extent to which these factors reduce actual victimization in everyday life.

Another randomized controlled intervention study focused on teaching identification of abuse situations and decision-making strategies to avoid or escape abuse (Hickson et al., 2015). Using the An Effective Strategy-Based Curriculum for Abuse Prevention and Empowerment (ESCAPE-DD) curriculum, classroom teaching took place in small groups over 12 sessions. Pre- and post-test assessment involved 6 brief, realistic, hypothetical vignettes describing sexual, physical, or verbal abuse. These written vignettes were read aloud, and participants verbally answered questions about each one. Intervention participants made greater gains on decision making, but problem awareness did not improve. The authors acknowledged that further curriculum development and research are needed before such interventions can assure that people with IDD are able to reduce their risk of abuse in real life.

While these findings are encouraging, there are limitations related to both teaching and assessment methods. For risk reduction training interventions to be truly effective, they must change knowledge and behavior, generalize to real-life situations, and be maintained over time. As the preceding examples show, teaching typically occurs in classroom-like settings and assessment involves verbal responses to hypothetical vignettes or role plays. There is evidence that classroom-based skill improvement by people with IDD may not generalize to real-life settings, whereas training in real environments may improve both generalization and maintenance (Fisher et al., 2013). However, such in-situ training adds time, cost, and logistic complexity that may be difficult to deliver at scale.

Demonstrating through research that people who have received these interventions behave in self-protective ways in real-life situations of potential abuse is quite challenging, partly for valid reasons of research ethics. It is not ethically appropriate to expose participants to the risk of victimization. Deception in research (e.g., use of research confederates) is usually not acceptable, although there are examples of confederates (strangers to the participant with IDD) being used to assess responses to aspects of stranger danger in real community settings (Fisher et al., 2013). In such circumstances there can be a tradeoff between ethical acceptability and assessment validity.

Theoretically, demonstrating a reduced rate of real-life victimization could be achieved by following a research cohort over time to assess prevalence of victimization. However, the highest prevalence rate for violent victimization during 2017–19 reported by Harrell (2021) for people with disability was for those aged 16–19 (179.0 per 1,000). Thus, even for this high-risk cohort, following them for 2 years post-intervention should mean that slightly more than 8 out of 10 had (fortunately) not experienced violent victimization, regardless of intervention status. To detect even large intervention effects under these circumstances would require a very big sample. Thus, researchers generally have looked at short-term treatment effects and evaluated verbal responses to realistic but hypothetical abuse scenarios. We know of no direct demonstration that such training leads to a lower risk of real-life victimization.

Measuring Safety Skills and Knowledge

There are challenges in developing valid and reliable instruments to measure knowledge and skills about victimization that people with IDD can understand and respond to (Dinora et al., 2021). At present, there is no gold standard tool; currently available tools are in various stages of development. Hughes et al. (2020) developed measures of outcomes of their study such as Knowledge of Healthy Relationships, Knowledge About Abuse, Knowledge of Warning Signs, and Safety and Communication Skills. However, difficulties with content and psychometrics led them to propose that further refinement of these measures was needed. Some tools involve answering questions about brief written, verbally presented (Hughes et al., 2020), or video-based (Dinora et al., 2021) fictional vignettes involving potential (sexual) abuse. However, Dinora et al. reported problems with the internal consistency of their measure, and there appeared to be issues with a ceiling effect. As noted previously, a critical issue is the extent to which responses to hypothetical vignettes generalize to real-life situations.

Needs and Preferences of People From Underserved Communities

Koh et al. (2021) noted the lack of diversity in disability research on abuse and exploitation, with very few studies examining the experiences of people from underserved communities. As identified by Dinora et al. (2021), most risk reduction programs for adults with IDD have focused on women with milder intellectual disability (see Khemka & Hickson, 2017) and rarely reported race and ethnicity, let alone analyzed intervention accessibility, effectiveness, and acceptability for different racial and ethnic communities. Several recent intervention studies have deliberately included men and women with IDD (Dinora et al., 2021; Hughes et al., 2020), but little is known about the needs and preferences of people with IDD from underserved communities regarding risk reduction programs.

Prevalence of Prisoners With Disabilities

Overall BJS disability data (Maruschak et al., 2021) revealed several important findings about U.S. adult prisoners (aged 18 and older). Prisoners (38%) were about 2.5 times more likely to report having a disability than adults in the U.S. general population (15%), indicating that people with disabilities were much more likely to be in prison than people without disabilities. The most common disability among prisoners was cognitive disability (23%). Black and Hispanic prisoners were less likely than White prisoners to report a cognitive disability (Maruschak et al., 2021). Prevalence of cognitive disability was higher among state prisoners (24%) than among federal prisoners (14%). This disparity may reflect the different types of crimes that lead to incarceration in state versus federal prisons.

Like other BJS data, Maruschak et al.’s (2021) results did not specifically identify people with IDD. The high prevalence of prisoners with cognitive disability suggests that people with IDD likely were overrepresented in prison but did not directly show this. International research typically has reported a disproportionately high percentage of prisoners with ID. In a systematic review, Hellenbach et al. (2017) concluded that the prevalence of ID among prisoners internationally was 7% to 10%, substantially above the prevalence of ID in the general adult population.

The BJS data just discussed related to inmates in U.S. state or federal prisons, but not those detained in local/city/county jails. Using 2011–12 national U.S. data, Bronson et al. (2015) reported a significantly higher prevalence of disability among jail inmates (40%) than among prisoners (32%). Cognitive disability (30.9%) was by far the most prevalent disability type among jail inmates, with a higher prevalence of cognitive disability than for prisoners in state or federal prisons (19.5%; Bronson et al., 2015). These findings clearly indicate that IDD research should focus on jails as well as prisons.

Are People With IDD From Underserved Communities Overrepresented as Offenders?

Interventions in the Criminal Justice System

There are multiple levels within the criminal justice system where people with IDD are seriously disadvantaged (Cooper et al., 2022). Each situation offers possibilities for improvement through changes in laws, policies, procedures, training of criminal justice personnel, and other interventions. Apart from the preceding discussion of victim’s compensation and the examination below of competence to stand trial, it is beyond the scope of this review to consider these issues in detail, although we acknowledge their clear importance.

Competency to Stand Trial

The right to due process means that if a person is found to be incompetent (unable to understand criminal justice processes such as their trial or to make informed decisions and assist their lawyer), then a trial cannot proceed. If competence is questioned by any party, the criminal court must determine the person’s competency. This is usually done by the judge ordering a competency evaluation. However, there are frequently very long waits for competency determinations (Boutwell, 2017; Brompton, 2017). While waiting, the person is often held in prison, a forensic psychiatric facility, or a secure IDD setting (Disability Rights California, 2023).

Self-evidently, competency issues are much more likely to arise for defendants with IDD than for most other defendants, so incompetency and its consequences should be seen as a disability-specific issue. However, there is a systemic problem that “the system is not designed to address competency of people with IDD, as exemplified by the lack of IDD-specific evaluations, restoration programs, resources, and expertise” (Brompton, 2017, p. 2). While the ideal is that “incompetency is only found in cases where there is a true lack of understanding that cannot be overcome with appropriate accommodations” (Brompton, 2017 p. 3), scant data are available on competency issues affecting defendants with IDD, with the result that many important questions remain unanswered.

Recent research has identified small but growing numbers of people with IDD moving from the criminal justice system to (secure) IDD public institutions and vice versa (Disability Rights California, 2023; Neidorf, 2023). This practice needs to be examined closely to determine who is affected, what outcomes they experience, and the relationship to competency determination and civil commitment.

Prevalence

There is consistent, robust evidence of high rates of victimization of people with disabilities, including people with IDD. In the United States, the National Crime Victimization Survey (NCVS; Harrell, 2021) identifies disability subgroups such as people with cognitive disability. IDD research, policy, and practice would be enhanced if participants with IDD in major criminal justice surveys, such as the NCVS, were identified separately. This could be achieved by adding items on core constructs of IDD, such as age of onset of the condition (Havercamp et al., 2019). As a household survey, the NCVS excludes people living in (disability) institutions causing “an undercount of violence against persons with disabilities” (Harrell, 2021, p. 10). More accurate prevalence estimates could be obtained by including people with disabilities not living in households. The NCVS collects data on both disability and racial/ethnic status, but in its publicly available reports, the BJS has only provided victimization prevalence data by racial/ethnic group for people with disability overall, not broken down by disability type (e.g., Harrell, 2021). Doing so would facilitate a clearer understanding of any disparities by race and ethnicity in the victimization of people with cognitive disabilities/IDD and provide advocates, policy makers, and researchers with ready access to this information.

Underserved Communities

There is limited criminal justice data on people with IDD from underserved communities. Hickson and Khemka (2021, p. 466) concluded that “The literature offered little clarity in terms of race/ethnicity and how it interacts with other risk factors.” We reached a similar conclusion regarding criminal victimization of people with IDD and noted that this gap applies to all aspects of criminal justice, not just prevalence and risk issues. Clearly, far more research is needed on all aspects of victimization of people with IDD and underserved community status.

One factor associated with why disability and underserved community membership are rarely examined together is the small sample size for some subgroups and consequent difficulties with statistical reliability. Even so, this does not explain the limited attention given to understanding the needs and preferences of underserved community members with IDD regarding criminal justice involvement.

Victim’s Compensation

More studies are needed to examine how people with IDD are aware of, understand, and utilize victim’s compensation schemes. This will help to identify barriers to access and effective supports and accommodations. Barriers/disparities by underserved community status should also be examined carefully. These goals require robust data on the number of victims/survivors with IDD who are informed about compensation, the number who apply for and receive compensation, and the amount and type of compensation granted.

Education and Intervention

Analyses of policy and practice in proactive education on sexuality, relationships, and personal safety are needed to document the current situation for people with IDD and, where possible, link this to data on the prevalence of victimization.

Fisher, Corr, et al. (2016) noted that few risk reduction programs had been developed. Recent years have seen further program development (e.g., Dinora et al., 2021; Hughes et al., 2020) and increasing research sophistication, including stronger research designs involving randomized control trials (RCTs; Hickson et al., 2015; Hughes et al., 2020). However, these efforts remain at the stage of curriculum development and evaluation, with no known examples of system-wide scale up, although both Dinora et al. (2021; 15 sites) and Hughes et al. (2020; 12 centers) involved multi-center trials with manualized intervention delivery. The outcomes of these classroom-based programs have been partially encouraging but generalization to real-world situations has not been demonstrated, and effectiveness in reducing actual victimization remains unknown.

None of the intervention programs has explicitly sought to understand victimization and self-protection from the perspectives of people with IDD from underserved communities and to develop effective interventions that are acceptable to those communities. Adequately responding to both the measurement challenges and the needs of underserved communities could ideally lead to future, scaled-up intervention studies with large enough samples to be followed over time to monitor the impact on real-world victimization.

Measurement

Measurement remains a challenge, and there is a clear need for further development to create valid, reliable measurement tools to evaluate interventions and to identify people with less well-developed knowledge and skills who would benefit most from relevant training. These tools should be evaluated for ecological validity to determine the extent to which the skills or knowledge assessed generalize to similar real-life situations. Further, such tools need to be examined separately with various underserved communities to determine their validity and acceptability for different cultural groups.

Prevalence

IDD research, policy, and practice would be enhanced if participants with IDD in major criminal justice surveys, such as the BJS Survey of Prison Inmates, were identified separately. Research is needed on the prevalence of people with IDD at all stages of the criminal justice system, including jail inmates, prisoners with IDD, and those held outside the prison system in secure IDD facilities.

Underserved Communities

More research is needed to provide robust and representative data on the prevalence of people with IDD at different stages of the criminal justice system and to evaluate outcomes, barriers, disability accommodations, and trends over time. One key focus of this research should be to document the proportions from different racial and ethnic groups in order to identify communities at high risk of criminal justice involvement, the circumstances of their involvement, and the variations in these patterns evident in different jurisdictions. This information can inform the targeting of risk reduction and diversion efforts and help ensure that such interventions are accessible and acceptable to the affected communities. Even with the very limited available research on these issues, the situation for young Black men with IDD warrants particular attention.

Specific issues for future research include examining crime and policing rates in the areas where people with IDD live and any disparities by race and ethnicity. Causes for living in areas with high crime and/or policing rates that could be investigated include housing affordability and poverty.

Competency

In-depth research is required on competency determination practices that are applied to defendants with IDD, including their validity, availability, timeliness, consequences, and the extent to which these issues differ for members of underserved communities. Likewise, robust data are needed regarding how the criminal justice, mental health, and IDD systems interact to deal with people who are waiting for competency assessment or reassessment. Specific questions include the following:

• Are competency determination processes valid and accurate for people with IDD, including people from diverse communities?

• How long do people wait for competency determination, and where do they wait?

• How many people judged as not competent end up detained in secure disability or psychiatric facilities (e.g., under civil commitment) and for how long?

• What community alternatives to prison or a secure facility exist for alleged offenders with IDD, and how does competency affect access to these alternatives?

• Do any of these competency-related issues function differently or have different consequences for people from underserved communities?