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MacArthur Juvenile Competence Study Results

Subjects range in age from 11 to 24, with 86 11- and 12-year-olds, 243 13- and 14-year-olds, 613 15- through 17-year-olds, and 470 18- through 24-year-olds (adults). About 40% of the total sample is African-American, 25% Latino, and 35% non-Latino White, relatively equally proportioned across the four study groups. Females comprise a little more than one-third of each of the four study groups. Socioeconomic status (SES) of the community groups was matched with the justice samples; lower SES characterizes about 70% of each of the study groups. Levels of intelligence are similar in the justice youths and justice adult groups, which are both considerably lower than the youth and adult community groups (as expected). Also as expected, levels of mental disturbance are generally higher for the justice youth and adult groups than for the community youth and adult groups.

Data were analyzed between mid-2001 and March 2002. In summary, we found that:

• Juveniles aged 15 and younger are significantly more likely than older adolescents and young adults to be impaired in ways that compromise their ability to serve as competent defendants in a criminal proceeding.
  
• Approximately one-third of 11- to 13-year-olds, and approximately one-fifth of 14- to 15-year-olds, are as impaired in capacities relevant to adjudicative competence as are seriously mentally ill adults who would likely be considered incompetent to stand trial by clinicians who perform evaluations for courts.
  
• Competence-relevant capacities of 16- and 17-year-olds as a group did not differ significantly from those of young adults.
  
• These patterns of age differences were robust across groups defined by gender, ethnicity, and socioeconomic status, and they are evident among individuals in the justice system and in the community.
  
• Juveniles of below-average intelligence are more likely than juveniles of average intelligence to be impaired in abilities relevant for competence to stand trial. Because a greater proportion of youths in the juvenile justice system than in the community are of below-average intelligence, the risk for incompetence to stand trial is therefore even greater among adolescents who are in the justice system than it is among adolescents in the community.
  
• Age differences were apparent with respect to individuals' performance on general measures of future orientation and resistance to peer influence. As a consequence, younger subjects, 11-14, likely manifest poorer understanding and reasoning about trials than do older adolescents and adults.

Adolescents are more likely than young adults to make choices that reflect a propensity to comply with authority figures, such as confessing to the police rather than remaining silent or accepting a prosecutor's offer of a plea agreement. In addition, they are less likely recognize the risks inherent in the various choices they face or to consider the long-term, and not merely the immediate, consequences of their legal decisions.