Guilty Before Proven Innocent: The Implications of Unconscious Racial Biases in the Criminal Justice System

Angelina Xu


Although a bedrock principle of the American criminal justice system is the presumption of innocence, research shows it might not always be upheld. This paper addresses various factors that can result in unjust rulings, including the cross-race effect, fallibility in memory, and the skin tone bias. These phenomenons can unintentionally incriminate innocents, especially African Americans at disproportionate rates. Given the science, how will the government and society address these issues?


Cross-Race Effect

In 2011, Otis Boone was convicted of two armed robberies and sentenced to 25 years in prison—based on identification by the victims and no physical evidence [1]. Seven years later, New York’s Court of Appeals cleared Boone of the charges. Two transaction records showed that Boone was one mile away during the time of the robberies. The judges also ruled that the jury should have been informed of the difficulty in identifying strangers of a different race: specifically, Boone was black; the victims were white.

Known as the cross-race effect, this phenomenon has been repeatedly demonstrated by studies that people are better at recognizing same-race faces, relative to other-race faces. This raises a major concern over eyewitness identification. In Boone’s case, the white victims wrongly accused a black man. As a result, Boone served seven years of someone else’s time. However, this is not an isolated case. According to the Innocence Project, of the 364 falsely convicted individuals who were later exonerated with DNA evidence, over 70% involved witnesses who identified the wrong assailant; almost half of those mistaken identifications involved a witness and suspect of different races [1]. Evidently, when cases involve parties of different races, society must reevaluate the role of witness identification in verdict decisions.

However, jurors and prosecutors consider the eyewitness’s confidence an important factor when assessing a testimony, even though the level of confidence has proven to be an unreliable indicator of accuracy, especially in cross-race identification. In one experiment, Caucasian and Asian subjects predicted their confidence (or lack of confidence) in remembering the same- or other-race face in a recognition test [2]. Caucasian subjects reported more confidence in future recognition of Caucasian faces while reporting less confidence in future recognition of Asian faces. Analogous results were seen in Asian subjects, who reported more confidence in the future recognition of Asian faces than in Caucasian faces. Yet, the subjects’ self-reported confidence inconsistently predicted the accuracy of other-race face recognition. For example, while Caucasian subjects may report confidence in remembering an Asian face in the later test, many fail to do so.

These mistaken cross-race witness accounts have grave legal implications: coupled with already faulty recognition (ie. the cross-race effect), faulty confidence could incriminate innocents. The devastating consequences materialized in the 1985 case of Ronald Cotton (a black man) after Jennifer Thompson (a white victim) falsely identified him as the assault perpetrator [3]. During the attack, Thompson vowed to remember the perpetrator’s face. Based on Thompson’s high self-reported confidence, the police believed that she would reliably recognize the face of the assailant in the line-up. Despite a second victim’s failure to select Cotton from the same line-up, Cotton was sentenced for life. Eleven years later, Thompson’s erroneous identification was overturned with concrete DNA evidence; Cotton was proven innocent.


Memory Fallibility

Considered compelling evidence by prosecutors and jurors, witness accounts and identifications have been warned by neuroscientists as susceptible to mistakes due to various other factors too. Besides the cross-race effect, stress, fear, and the crime incident’s short duration may prevent the viewer from perceiving the event accurately. The science of memory has shown that recollective experiences are often fragmentary and out of order [5]. The witness’s brain unconsciously rearranges the events and fills in the gaps to create a coherent narrative of the incident. However, this coherence comes at the expense of accuracy. Thus, when eyewitness memory is provided to the law, the evidence can be fallible at best and unreliable at worst.


Skin Tone Bias

Furthermore, researchers have used functional magnetic resonance imaging (fMRI) to explore the correlation between skin tone bias and amygdala activity [6]. The amygdala region of the brain is stimulated by fast, unconscious assessments of potential threats. When subjects were presented photographs of darker-skinned individuals, higher levels of amygdala activation were observed, signifying the association of darker skin with danger. Combined with the aforementioned unreliable memory, the preconceptions of dangerousness may alter the witness’ perceptions.  They may falsely remember a black defendant’s actions as threatening or mistakenly imagine he was carrying a weapon. Ultimately, this subconscious stereotyping disproportionately incriminates African Americans on false premises.

Ramifications of this unintentional stereotyping are evidenced in another empirical study. Mock jurors who saw a photo of an armed robber with dark skin judged subsequent ambiguous evidence as notably more probative of guilt than did mock jurors who saw the identical photo with the armed robber being light-skinned [8]. Although the mock jurors’ racial-based judgments were unintentional, they undermine a core principle of US criminal law: the presumption of innocence. Instead, black defendants—especially those with darker skin tones and greater Afrocentric features—are subject to the presumption of guiltiness [9]. The evaluation of successive trial evidence is injected with racial bias, resulting in more frequent guilty verdicts and harsher sentences. These unconscious racial perceptions based on physical features raise concerns on the integrity and legitimacy of the criminal justice system.



With the recent cries of “I can’t breathe” and “Say her name” for racial equality, society must also consider the steps that must be taken to ensure fairness for African Americans in criminal law. After Boone’s ruling, New York has required the jury to understand the cross-race effect before making informed decisions. But New York is only one of the few states to address this issue. Even so, when people unintentionally associate Afrocentric features with danger, how fair are the verdicts? What can be done to diminish the effects of this phenomenon when people are seemingly unaware of its influence? With science questioning the legitimacy of witness identifications and memory, how will law enforcement view these long-held, reliable types of evidence? Should all testimonies and identifications be viewed with skepticism? In the event that there is no concrete evidence like video footage or DNA tests, can verdicts then—and only then—be made solely based on memory? If wrong convictions are later overturned, who should be responsible for the psychological damage and lost opportunities caused by imprisonment?  More importantly, how may this contribute to the ever-perpetuating cycle of black mass incarceration? With racial inequity and public safety at play, these ambiguities beg the question: Should we imprison innocents or allow criminals to roam free?


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  3. O'Neill, H. (2001). The Perfect Witness. Death Penalty Information Center. Retrieved: 30/06/2020.

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  7. Duke University. (04/02/2015). A Brain Marker Pinpoints Vulnerability for Future Life Stress. Retrieved: 26/08/2020.

  8. Bennett, M. W., & Plaut, V. (30/11/2017). Looking Criminal and the Presumption of Dangerousness: Afrocentric Facial Features, Skin Tone, and Criminal Justice. UC Berkeley Public Law Research Paper. Retrieved: 02/07/2020.

  9. Maule, A., & Zack, E. (15/02/2019). #BlackBehindBars: A system designed to break you down. Innocence Project. Retrieved: 02/07/2020.

  10. Levinson, J. D., Young D. (10/05/2010). Different Shades of Bias: Skin Tone, Implicit Racial Bias, and Judgments of Ambiguous Evidence. West Virginia Law Review. 112, 307-350. Retrieved: 26/08/2020.

Angelina Xu

Angelina Xu

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