Major Mental Illness as a Risk Factor for Incarceration

A wide body of literature attests to the overrepresentation of individuals with major mental illness in the criminal justice system. Recent estimates suggest that more than 2 million people with a serious mental illness are booked into jails each year and that prevalence rates of current serious mental illness for recently booked jail inmates are approximately 15% for men and 30% for women (1). Estimates of serious mental illness among state prisoners are lower, ranging from 6% to 14% (2). These estimates compare with community estimates of approximately 4% (3).

Despite increased attention to the relationship between mental illness and criminal justice system involvement, research has focused largely on individuals who are already incarcerated. Overrepresentation within the correctional system may be the result of a disproportionate prevalence of individuals with major mental illness among arrestees or may be related to differential treatment of individuals with major mental illness who are exposed to the justice system.

Prior research has identified a variety of case- and defendant-related factors that affect the likelihood that an arrest will result in conviction and incarceration. These include legal considerations such as offense seriousness, strength of the evidence, and seriousness of the defendant’s criminal history, as well as extralegal considerations such as race, gender, and age. These factors also include socioeconomic status, particularly through its effect on pretrial incarceration.

Offense seriousness and prior criminal history are commonly referenced within the criminal law as principal factors to be considered in sentencing decisions, and research has confirmed their centrality to the plea and sentencing process (4). Strength of the evidence also affects plea bargaining decisions (5) and can render personal offenses, which frequently rely on victim testimony for prosecution, less likely to result in conviction than property and drug offenses (6, 7).

Although the outcomes of criminal arrests are largely determined by these legal considerations, extralegal factors can also affect the trajectory of criminal cases. Studies have generally found that female defendants are treated more leniently than similarly situated male defendants (8). Likewise, white defendants are often treated more leniently than nonwhite defendants (9–11). The more severe outcomes for nonwhites may be related to their pretrial release status. Research has shown that nonwhites are more likely to be incarcerated pretrial, and defendants who are incarcerated pretrial are more likely to be convicted and sentenced to incarceration (6, 7). These extralegal factors often exert greatest influence in situations in which decision makers have greatest discretion, such as in misdemeanor cases, where plea and sentencing decisions may be less structured by statute (12–14).

A defendant’s major mental illness also may influence the trajectory of a criminal case. Major mental illness can be a legal consideration if the illness interferes with a defendant’s competency to stand trial and/or the defendant meets criteria for an insanity plea. In New York State, misdemeanor charges are dismissed when a defendant is found incompetent to stand trial (15). Prosecutions are also terminated in New York State when a defendant is found not responsible because of mental disease or defect (16). These mental health–related terminations of criminal prosecutions are very uncommon in the state. For example, in 2016, 149,562 felony arrests and 328,058 misdemeanor arrests occurred throughout the state (17); and that same year, only 710 misdemeanor cases were terminated with a finding of incompetence to stand trial and 36 felony cases were terminated because the defendant was found to be not responsible due to mental disease or defect (18). Last, a defendant’s “mental condition” is a statutorily defined factor that may be considered in bail determinations in New York State (19). Trial courts have interpreted this section as allowing defendants to be held in jail pending insanity plea proceedings (20).

A defendant’s mental illness also may affect the trajectory of a criminal prosecution as an extralegal consideration. It may serve as a mitigating or aggravating factor in the plea or sentencing process, despite the absence of underlying statutory authority. A defendant with a major mental illness may be viewed by decision makers as less culpable than a defendant who is not mentally ill or perhaps as more vulnerable to the negative consequences of incarceration. Conversely, such a defendant may be viewed as inherently more dangerous than a similarly situated defendant who is not mentally ill and thus more likely to be prosecuted and incarcerated.

The twofold purpose of this study was to utilize New York State arrest data, Medicaid data, and data from the state’s Office of Mental Health to measure the prevalence of major mental illness, as defined by a recent diagnosis, among individuals arrested and to determine whether a diagnosis of a major mental illness is related to severity of sanction. The goal is to broaden the understanding of the interplay between major mental illness and criminal justice involvement and outcomes.

Methods

Data Sources

Arrest data.

The arrest sample included all persons arrested for a felony or misdemeanor crime, other than a vehicular and traffic offense, in New York State between January 1, 2010, and December 31, 2013. If an arrestee appeared more than once during that time period, only the first arrest was included in the sample. As such, this is a person-based rather than event-based analysis. A person-based measurement removes the weighted effects of high-rate repeaters on the research findings. Although this strategy allows us to measure the point prevalence of persons with a recent major mental illness diagnosis among this sample of arrestees, it does not support a measure of the period prevalence of a correctional population. There were 602,181 defendants in the sample, 533,351 (89.6%) of whose arrest was fully adjudicated at the time the data were extracted in May 2015. Defendants whose arrest was not fully adjudicated at time of data extraction were removed from the sample.

The arrest data were drawn from the state’s Computerized Criminal History data file maintained by the Division of Criminal Justice Services. These records include measures of the arrest event (type and penal law class of the most serious arrest charge in the event, whether any of the arrest charges involved a statutorily defined violent felony offense or a firearm offense, and jurisdiction in which the arrest occurred). In addition, the records included information on the disposition of the arrest event (conviction and sentence type) and lifetime prior criminal history of the arrestee in New York State (numbers of prior arrests involving felony, misdemeanor, or combined felony and misdemeanor; adult prior felony convictions; prior youthful offender felony convictions; prior violent felony offense convictions; and prior firearm convictions). The records also included demographic information about the arrestee (age, gender, and race). In addition, this research further classified the arrest as violent or nonviolent, with violence defined as involving any of the following arrest charges: assault and related offenses (Penal Law Section 120); strangulation and related offenses (Penal Law Section 121); homicide and related offenses (Penal Law Section 125); sex offenses (Penal Law Section 130); kidnapping, coercion, and related offenses (Penal Law Section 135); robbery (Penal Law Section 160); sexual performance by a child (Penal Law section 263); firearms, dangerous weapons, and related offenses (Penal Law Section 265); and terrorism (Penal Law Section 490). Although the violent felony offense and violent crime measures overlap, the statutorily defined violent felony offense measure includes some types of burglaries, which are not included in our measure, and the violent crime measure, developed for this research, includes many lower level crimes of violence that are not statutorily defined violent felony offenses.

Mental health data.

Two sources of mental health data were used in this research: Medicaid billing records for mental health services and admission and discharge records from the Mental Health Automated Record System maintained by the Office of Mental Health. Although there is overlap between these two samples of mental health records, most Medicaid-reimbursed mental health services are not provided by the Office of Mental Health hospital system, and, conversely, a portion of those served by the Office of Mental Health system are not in the Medicaid system. The time frame for the mental health services sample extended from January 1, 2009, to December 31, 2013. This sample of approximately 1 million mental health service recipients was matched to the arrestee sample by using probabilistic matching software that matched on multiple identifiers, including name, date of birth, and Social Security number. Major mental illness was indicated by the presence of any of the following diagnoses in one or more treatment episodes in the year prior to the defendant’s arrest: schizophrenia, schizoaffective disorder, other psychotic disorder, bipolar disorder, manic affective disorder, and major depressive disorder. The data were originally compiled for operational purposes, and personal identifiers were deleted prior to this research analysis. Thus, the reviewing institutional review board determined that the project did not meet the criteria for human subject research.

Data Analysis

This analysis measures whether defendants who had been treated in the public mental health system for a major mental illness in the year prior to their arrests received more severe sanctions than defendants without such diagnoses during that time frame. Defendants who were identified as having a treatment episode with one or more of the aforementioned diagnoses had, on average, 11 treatment episodes in which they received one of the diagnoses. A severe sanction was defined as any term of incarceration for a defendant charged with a misdemeanor and a prison sentence for a defendant charged with a felony. The analysis was conducted separately for the sample of defendants with misdemeanors and the sample with felonies.

Binomial logistic regression was employed to estimate the unique effect of a diagnosis of major mental illness on the case outcome and explore whether other control variables modulate it. Binomial logistic regression utilizes a dichotomous dependent variable (for example, jail or no jail) and produces an equation that estimates the unique contribution of the independent variables (which may be dichotomous, categorical, or continuous) in predicting the dependent variable.

Results

Misdemeanor Arrestees

The initial sample included 407,172 misdemeanor arrests, 355,923 of which were disposed at the time of data extraction. Individuals with a major mental illness diagnosis were slightly more likely to have their case disposed than those without such a diagnosis (91% versus 87%, r=.03). The final misdemeanor sample included 355,923 arrestees, approximately 20% of whom received a jail sentence (Table 1). For the purpose of this research, a jail sentence was defined as a straight jail term, a combination of probation and jail term, or a “time served” sentence. Nearly 6% of the sample had been given a diagnosis of a major mental illness in the year prior to their arrest (Table 1).

Results of the logistic regression for misdemeanor arrestees are presented in Table 2. The listwise deletion of cases with missing data resulted in a .7% reduction in sample size from 355,923 to 353,344. A major mental illness diagnosis in the year preceding the arrest was significantly associated with increased odds of a jail sentence, independent of the control variables (odds ratio [OR]=1.52, 95% confidence interval [CI]=1.47–1.57). Most of the control variables were also significantly associated with the likelihood of a jail sentence given a misdemeanor arrest. Model 1 provides the odds ratios without interaction effects included in the equation. Males were more likely than females (OR=1.32, 95% CI=1.28–1.35) and nonwhites were more likely than whites (OR=1.17, 95% CI=1.15–1.20) to receive a jail sentence in this model. Nearly all the prior history measures were significantly and positively associated with the likelihood of a jail sentence, as was having a Class A instant offense (OR=1.30, 95% CI=1.27–1.33). The presence of violence in the instant offense, however, reduced the odds of a jail sentence (OR=.57, 95% CI=.56–.59). One control variable–region of arrest–was modeled as a categorical measure with three categories: New York City; metro New York, which consisted of Suffolk, Nassau, and Westchester Counties; and upstate, which consisted of all of the remaining counties in the state. Upstate was the reference category. The odds of a jail sentence were higher in New York City (OR=1.10, 95% CI=1.08–1.13) and metro New York (OR=1.39, 95% CI=1.35–1.44), than upstate.

Model 2 shows the results of adding interaction effects between major mental illness diagnosis and age, race, gender, and violent arrest offense. The only statistically significant interaction effect occurred between a diagnosis of major mental illness and age.

Felony Arrestees

The same procedures were utilized to model the effect of mental health status on the probability of a prison sentence given a felony arrest. The independent variables in the felony equation were largely identical to those described above. Class of arrest offense, however, was measured as an interval level variable ranging from 1 (class E, lowest level felony) to 6 (class A-1, highest level felony). In addition, the felony equation included a measure of whether the arrest involved a firearm charge or a violent felony offense charge.

The initial felony sample included 195,007 felony arrests, 177,426 of which were disposed at the time of data extraction. Cases involving individuals with and without a diagnosis of major mental illness were equally likely to be disposed at the point of data extraction. A total of 4.4% of the felony arrestees had a major mental illness diagnosis in the previous year and 12.2% received a prison sentence for the felony charge (Table 3).

Results of the logistic regression for felony arrestees are presented in Table 4. The listwise deletion of cases with missing data resulted in a 1% reduction in sample size from 177,426 to 175,692. A diagnosis of a major mental illness was not significantly associated with the likelihood of a prison sentence given a felony arrest (OR=1.06, 95% CI=.98–1.14). Most of the measures of charge seriousness and prior criminal history were significantly and positively associated with receipt of a prison sentence. Two prior criminal history measures decreased the odds of a prison sentence, but both effects, though statistically significant, were weak. A current charge involving violence increased the odds of a prison sentence (OR=1.68, 95% CI=1.60–1.77), as did a charge that was statutorily defined as a violent felony offense (OR=1.28, 95% CI=1.22–1.34). The odds of a prison sentence more than doubled for each penal law class increase in the arrest charge (OR=2.15, 95% CI=2.12–2.18). Males were twice as likely to receive a prison sentence as females (OR=2.01, 95% CI=1.90–2.12), after control for the other case characteristics, and nonwhites were marginally less likely to receive a prison sentence than their white counterparts (OR=.94, 95% CI=.90–.98).

Despite the absence of an association between a major mental illness diagnosis and a prison sentence for a felony offense, additional modeling was undertaken to determine whether a major mental illness diagnosis exerted a moderating effect in the prediction equation. Interactions between major mental illness diagnosis and age, race, gender, firearm arrest, and violent offense arrest were added to the model. Major mental illness was shown to interact with race (OR=.66, 95% CI=.56–.77), such that the odds of a prison sentence were 6% lower for nonwhites without a major mental illness and 38% lower for nonwhites with a major mental illness. Major mental illness also modulated whether being charged with a violent offense resulted in a prison sentence (OR=1.28, 95% CI=1.09–1.50), such that being charged with a violent crime increased the odds of a prison sentence by 68% for defendants without a major mental illness and by 114% for those with a major mental illness diagnosis. Last, major mental illness interacted with age such that the inverse relationship between age and a prison sentence was slightly stronger for defendants with a diagnosis of a major mental illness (OR=.99, 95% CI=.98–1.0).

Discussion

The prevalence of a recent major mental illness diagnosis among defendants in this research was lower than estimates of serious mental illness within correctional populations. As noted earlier, this was a person-based analysis and thus cannot be extrapolated to a cross-sectional measure of a correctional population. If, because of legal or extralegal factors, mentally ill defendants are more often incarcerated than defendants who are not mentally ill, serve longer terms of incarceration, or are more often rearrested, their prevalence in a correctional population would exceed their prevalence among a sample of defendants.

A diagnosis of a major mental illness in the year prior to an arrest had a variable impact on the likelihood of a severe sanction as measured by jail for misdemeanor arrestees and prison for felony arrestees. On the one hand, it exerted no direct influence on the likelihood of a prison sentence given a felony arrest, but it did modulate the effect of race, violence, and age on the likelihood of a prison sentence. The interaction between a major mental illness diagnosis and a violent offense charge could reflect greater concerns (perhaps exaggerated) about future violence, differences in the nature of violent offenses for arrestees with major mental illness that were not explored here, or the effect of an unmeasured variable such as pretrial incarceration (as discussed below). The interaction between mental illness and race was unexpected and should be subject of further study.

For misdemeanor arrestees, major mental illness was associated with more than a 50% increase in the odds of a jail sentence. These findings are consistent with the results of other research showing that extralegal factors exert the strongest influence in less serious cases where discretion is greatest (8).

This study had several limitations. First, the measure of major mental illness is limited. Some arrestees with symptoms of a major mental illness would not have received treatment in the year prior to arrest. Moreover, the measure is confounded by socioeconomic status. The public mental health system is more likely to treat recipients with limited financial means; impoverished defendants are more likely to be incarcerated pending trial, and defendants who are incarcerated pending trial are more likely to receive sentences of incarceration (6). To clarify this potential confounding effect, one would need a measure of socioeconomic status and pretrial release status for all defendants in the sample, which was not available in the data. Last, these results reflect the interplay between the mental health and criminal justice systems in New York State and may not be representative of outcomes in other states.

Conclusions

Much research has focused on the high rates of mental illness within criminal justice settings, with most attention on the disproportionate representation within correctional settings. Little attention has been paid to disparities at earlier stages of case processing. This study examined major mental illness and case outcome and found that while a diagnosis of major mental illness was associated with incarceration among misdemeanor arrestees, it was not related to the likelihood of a prison sentence among felony defendants. This disparity in outcome within the misdemeanor sample may partially explain the disproportionate representation of individuals with mental illness in jails throughout the United States. More research is needed to assess the role that pretrial incarceration may play in the heightened use of incarceration for mentally ill defendants charged with misdemeanor-level offenses.