In April 2009, Sheriff's Officer Matt Darisse stopped Nicholas Heien and Maynor Javier Vasquez because the right brake light of Heien's car was not working properly. Darisse believed this violated North Carolina's statute on the required lighting equipment on vehicles. However, the statute mandates that vehicles be equipped with only one working brake light. Following the stop, Darisse issued a warning citation for the light, obtained permission from Heien to search the car, and found a sandwich bag filled with cocaine. Heien and Vasquez were charged with trafficking offenses. Now, the U.S. Supreme Court must determine whether an officer's reasonable mistaken belief about the law can form the basis for reasonable suspicion, which is required to ensure that traffic stops and subsequent searches and seizures do not violate individuals' Fourth Amendment rights (Heien v. North Carolina).
A number of amicus curiae briefs have been filed in this case, but so far only one has addressed issues related to race and ethnicity and the Fourteenth Amendment's equal protection guarantee. The brief by The Rutherford Institute argues that allowing police latitude in their interpretation of the law will have a disparate impact on minorities, because evidence shows that African-Americans and Hispanics are more likely than whites to be searched. The brief did not, however, reference the social psychological research demonstrating that cultural stereotypes cause thoughts of race and ethnicity to be automatically associated with thoughts of crime and, in turn, bias how people perceive others and, ultimately, behave.
For instance, police have been shown to perceive African-American faces as looking more criminal than white faces (Eberhardt, Goff, Purdie, & Davies, 2004; for a review, see Najdowski, 2014). Such findings are concerning because they suggest that police may be subject to confirmation bias in their information processing: They may assume the criminal stereotype is true in a given case, focus their attention on evidence that confirms the stereotype and more frequently come to incorrect conclusions about the law when interacting with minorities than with whites. In the current case, Vasquez, who is Hispanic, was driving while Heien slept in the back seat of the car. Did Vasquez's ethnicity set off a series of social psychological processes that led to Darisse's mistake of law? Experimental research could explore this question, but the extant literature suggests that allowing discretion in this arena could increase the likelihood that officers will see crime where there is none when interacting with minority citizens.
There is another mechanism by which stereotypes could contribute to racial and ethnic disproportionality in police mistakes of law. My research suggests that expecting to be judged and treated unfairly due to negative stereotypes linking race and ethnicity to criminality may cause minorities to behave more nervously and "suspiciously" than whites in encounters with police officers. Because police often rely on citizens' behavior when determining what actions to take, minorities' experiences of stereotype threat and its behavioral consequences may lead police to initiate more investigatory contacts with minorities than with whites (Najdowski, 2014). In this case, Darisse testified that he began following Vasquez because he "thought Vasquez appeared ‘stiff and nervous,' insofar as he was ‘gripping the steering wheel at a 10 and 2 [o'clock] position, looking straight ahead'" (Heien v. North Carolina, No. 13-604). Thus, not only could stereotypic associations directly influence police officers' perceptions in ways that lead them to focus disproportionately on minorities as potential suspects, but minorities' awareness of that risk and resulting behavior could be misperceived by police as evidence supporting the criminal hypothesis. This could exacerbate the likelihood of confirmation bias, thinking errors and mistakes of law in cases involving minority individuals.
Heien is an important case addressing the constitutionality of traffic stops made on the basis of police officers' reasonable mistakes of law. It raises serious concerns about protections that ban unreasonable searches, and because officers may be overly inclusive when deciphering whether minority citizens' actions amount to legal violations, it also has implications for the promise of equal protection under the law. Psychological research can inform this issue.
