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July 20, 2021 Feature

Redefining Bias in Criminal Justice

Richard Gabriel, John G. McCabe, and Rebecca C. Ying

In the wake of the death of George Floyd in 2020, it is estimated that protests occurred in over 2,000 cities in 60 countries worldwide and that between 15 and 26 million people protested in the United States alone. Two hundred cities imposed curfews, almost 100,000 National Guard troops were deployed, and at least 14,000 people were arrested in the 7,305 demonstrations. Monuments were torn down, buildings were renamed, police reforms were introduced, and “systemic racism” and “social justice” became common phrases in news stories.

When police officer Derek Chauvin was tried for George Floyd’s murder, over 300 jurors filled out a 14-page questionnaire (see Special Juror Questionnaire, Minnesota v. Chauvin, Court File No. 27-CR-20-12646 (2020), where they were asked questions about their participation in protests, experiences and attitudes toward the police, and media exposure to the circumstances of George Floyd’s death, among other questions. Early in the questionnaire, they were also asked this question:

No matter what you have heard or seen about this case, and no matter what opinions you might have formed, can you put all of that aside and decide this case only on the evidence you receive in court, follow the law, and decide the case in a fair and impartial manner?

As in-person criminal trials are resuming, jurors will no doubt be asked in voir dire about their attitudes toward the police and the criminal justice system as well as their reaction to the Derek Chauvin trial and verdict. If they express any type of opinion or belief, or recount an experience that evinces bias, they will certainly be asked if they can set that aside and decide the case based only on the evidence and the law. Many will say and believe that they can, but most will be wrong.

The criminal justice system has a bias problem, but it may not be the one you are thinking of. The founders of this country understood the importance of impartiality in a justice system. What the drafters of the Sixth Amendment and our current criminal justice system fail to understand is how the human mind operates.

Courts think of the concepts of “bias,” “fairness,” “impartiality,” and “open-mindedness” as static and binary states. A juror has a bias or does not. They can either be fair or they cannot. They can be open minded or not, impartial or not. Rather, these concepts are dynamic processes that may change constantly during a trial depending on how a juror reacts to the witnesses, evidence, attorneys, and the judge. Courts also tend to prefer the concept of the “blank slate” juror: a juror who can compartmentalize or “set aside” past experiences and beliefs and only consider the evidence and law in a given case. Courts also adhere to the belief that jurors will be able to conform their mindsets to whatever the court instructs them to do. They will completely disregard what the court tells them to disregard and only download into a special folder in their brains the evidence and law that the court allows. Operationally, it is understandable that institutions want to standardize definitions. However, these idealized and antiquated concepts create significant obstacles to the concept of impartial justice that is so important to our system.

In our current culture, we have the ability to instantly Google and familiarize ourselves with the given issues in a case. Our social media bubbles constantly reinforce our currently held beliefs with selected news and opinion feeds. Both of these habituated practices we use on a daily, if not hourly basis pose significant obstacles to impartiality and open-mindedness.

This article seeks to help judges and counsel to better understand how bias operates and affects a juror’s ability to be fair and impartial. We will further discuss procedures that will allow the judges and lawyers in a given case to make better-informed choices on cause and peremptory challenges, to instruct jurors, and to assist them in monitoring themselves for experiences and attitudes that may affect their own ability to be fair and impartial and to keep an open mind.

Defining Bias

During voir dire, the courts typically legally define three types of bias: (1) actual or explicit bias, (2) implied bias, and (3) inferable bias. Actual bias is where a juror expresses a bias and the court evaluates the sincerity of that expression and how it might affect their ability to sit as a juror. Implied bias is where the court typically evaluates whether the juror has a relationship to one of the parties in the case that would affect their ability to sit as an impartial juror. An inferable bias is where a juror has an experience, belief, or opinion that would affect their ability to serve impartially. Most judges do not have a problem with evaluating the first two categories of bias. However, the courts and attorneys have great difficulty with this third, and most common category of inferable bias.

In evaluating bias, judges and attorneys assume that jurors consciously know their own biases and the effect that those biases will have on future decision-making. See R. Nisbett & T. Wilson, Telling More Than We Can Know: Verbal Reports on Mental Processes, 87 Psych. Rev. 231 (1977). When judges address the possibility that a juror may have an unconscious (or “implicit”) bias as a result of an experience or belief, judges believe that jurors can both identify the bias and actively control that bias. See D.T. Wegener & R.E. Petty, Flexible Correction Processes in Social Judgment: The Role of Naïve Theories in Corrections for Perceived Bias, 68 J. Personality & Soc. Psych. 36 (1995).

As a result, judges and attorneys rely on phrases like “set it aside” (as if a bias were an object that they could put on a shelf), “put that out of your mind” (make the bias disappear), “But you can still be fair and impartial, right?” (ignore the bias), or “But you can still faithfully follow the court’s instructions and decide the case on the testimony, evidence, and law, correct?” (instruct away the bias). Even if the juror who is told one of these phrases makes a good faith attempt to correct for their biases, they typically cannot do so successfully for the reasons we identify below.

  • A bias in judgment is basically anything that tends to move judgments of an idea, object, action, individual, or group away from an (often idealized) objective, rational evaluation. See, generally, Heuristics and Biases: The Psychology of Intuitive Judgment (T. Gilovich, D. Griffin & D. Kahneman eds. 2002). In other words, a bias is not a thing but a force that influences judgment. Social science research is replete with examples of people’s beliefs, experiences, and attitudes biasing their judgment. Additionally, a juror’s potential bias in judgment can have many sources. (More information on these and other psychological terms can be found at
  • Prejudice literally means to prejudge people negatively before ever having any experience with that person or group. It is especially resistant to change because the prejudice also serves to filter out incoming positive information about the target people or groups. While prejudice is often associated with racial bias, prejudice can also relate to religion, culture, geography, sexual orientation, gender, and occupation. Our current polarized political climate in this country also makes this type of bias a pervasive problem. A prejudiced juror cannot be impartial and would violate the court’s admonition to “keep an open mind.”
  • Preconception tends to refer to judgments of things other than people, while having little or no direct experience with the matter. In criminal cases, preconceptions about law enforcement, prosecutorial agencies, gangs, financial institutions or corporations in white-collar cases, and even the justice system itself can be a source of jurors’ expectations and can bias judgments if the case facts align with or defy these expectations.
  • Stereotypes, like prejudices, generally relate to people but are (exaggerated) generalizations about the characteristics of a group or social category. Stereotypes tend to be negative but can also be positive. Also, like prejudices, stereotypes are resistant to correction because they tend not to change even when people encounter others who defy that group’s stereotype. When we do not have much information about a group of individuals, we tend to stereotype. As we will discuss later, when judges and attorneys do not ask questions that relate to a juror’s potential biases or do not have enough time to understand the juror’s relevant experiences or opinions, they tend to use stereotypes in the form of demographic categories (gender, age, education, race, etc.) to make jury selection decisions. This problematically then runs into Batson and other state statute prohibitions against making discriminatory challenges based on protected classes. Additionally, a juror who uses stereotypes as part of their decision-making process about a witness, party, or attorney cannot be said to be impartial.
  • Preference refers to choosing one alternative over others and connotes a much milder form of bias. Preferences can be a positive or negative association or an inclination and is usually formed from life experiences or habit. For example, in working on the O.J. Simpson case, our research showed, not surprisingly, that white jurors attached a positive association with the police while Black jurors in Los Angeles tended to have a negative association. These associations or preferences tended to color their views of the police investigation, despite the evidence in the case. In the Casey Anthony case, we knew that jurors’ common association that a mother would immediately report a missing child would incline them toward the guilt of Ms. Anthony, who did not report her child missing for 31 days. Preferences, inclinations, and associations can be forms of bias in judgment depending on how relevant they are to the judgment and how strong they are.

There are numerous other cognitive biases such as confirmation bias, hindsight bias, availability bias, and the fundamental attribution error. By themselves, these psychological blind spots may not rise to a challengeable bias but depending on a juror’s experience and beliefs can be activated during a trial. In analyzing the juror questionnaires in the Phil Spector case, we discovered that approximately half of the jurors believed that it was the defendant’s burden to prove his innocence and that they expected an innocent defendant to testify on his own behalf. While some of those jurors clearly were able to reform this belief after hearing a judge’s instruction, many found this counterintuitive and struggled with the concept.

Rather than adhering to antiquated but legally precedential concepts of bias, there are three categories of bias awareness that judges and attorneys should pay attention to in gauging a juror’s ability to recognize whether a life experience, attitude, or belief impairs their ability to be fair and impartial.

Conscious bias. This is where a person is aware of their bias, they can talk about it, and they can make an attempt to correct for it. This is the easiest type of bias for a judge to identify because there is direct evidence of the bias. A juror in a criminal trial may say, “I don’t like the police. They locked up my brother when he did nothing wrong.” The juror’s lack of impartiality is overt and obvious.

However, another type of cognitive bias can come into play when a juror expresses an obvious bias: the social desirability bias. This is people’s tendency to present themselves in a way that will be viewed favorably by others. When judging others, fairness and impartiality are socially desirable traits, so prospective jurors are reluctant to present themselves as anything other than completely unbiased. See Irvin v. Dowd, 366 U.S. 717 (1961) (in which “8 of the 12 who finally served on the jury admitted that they thought petitioner was guilty, but each indicated that, notwithstanding his opinion, he could render an impartial verdict”). Aside from some jurors who express biases to try and get out of jury duty, few jurors want to be seen as prejudiced, as relying on negative stereotypes, or basing their decisions on preconceptions on topics on which they know little or nothing. As a result, the juror may not mention their conscious biases. If they do express the bias, a judge or defense attorney may then try to rehabilitate this juror and ask them if they can set aside their feeling about the police in order to judge the evidence fairly and impartially, and they may agree in order to not look like they are an unfair person to the judge and a group of strangers. This is why judges and attorneys should always attempt to foster open and honest interactions with potential jurors to encourage them to be frank about beliefs, attitudes, or experiences that they know they have, rather than strong-arming them into disavowing their conscious biases. See D. Suggs & B.D. Sales, Juror Self-Disclosure in the Voir Dire: A Social Science Analysis, 56 Ind. L.J. 245 (1981).

Unconscious, but correctable bias. Once a person is made aware of a bias or is able to attribute the biasing effect to some other source, they can correct for it. People may be able to self-report this kind of bias after it has been brought to consciousness.

In the classic psychological experiment reported by Norbert Schwarz and Gerald L. Clore in 1985, they found that people reported lower overall life satisfaction on rainy days and higher overall satisfaction on sunny days. However, when the interviewer added the question “By the way, how’s the weather down there?” before the interview, respondents became aware of the weather, then corrected for its biasing effect in assessing their total life satisfaction.

Thus, if a juror is made aware of the potentially biasing impact of a belief, attitude, or experience, then it is possible for the juror to attempt to correct for it. The problem, of course, is that jurors may not correct, may undercorrect, or may overcorrect and the judge has absolutely no way of knowing.

For example, in the second Aaron Hernandez murder trial, many of the jurors had seen publicity about his first trial and conviction as well as the impending second trial. When asked about it, many stated they did have the impression that he was probably guilty of this alleged murder as well. However, when confronted with this presumption of guilt, there were jurors who genuinely admitted that they did not know anything about the facts of the second case. Once aware of a bias, a juror can make an effort to distinguish between the evidence and their preconceptions.

But here is the difficulty in a case with any pretrial publicity or where a juror has a conscious or unconscious bias: We are relying on a juror’s willingness to “set aside” that bias without knowing how they will set it aside. Instead, we need to better understand the nature of the bias: the length of time that they have had the experience or held the belief and the strength of their conviction in that experience or belief. Additionally, judges and lawyers need to evaluate the self-awareness of jurors—their ability to identify and discern between the evidence or law and their own bias. Contrary to legal definitions of bias, it is not the existence of a bias that renders a juror unable to be fair and impartial; it is how that bias affects their judgment in a case.

Judges are often satisfied if jurors say they will try to set aside the bias. An attempt to correct a bias is not good enough. The parties in a case are entitled to a completely impartial jury, not a partially impartial one or a juror who is merely endeavoring to be impartial. Imagine a couple getting married and when one is asked if they will be faithful, the soon-to-be spouse says, “Well, I’ll try.” The oath a juror takes is no less meaningful to the parties involved than wedding vows.

Unconscious (sometimes called “implicit”) bias. This is a bias that a person has no conscious awareness of. Attempts to bring this bias to consciousness, so that the person can make an attempt at correcting for the bias, will fail.

There are a few means to unearth unconscious biases, most notably the Implicit Association Test, or IAT. The IAT is a timed test that measures the strength of people’s association between concepts, for instance, the word “good” or “bad” and a Black face or a Caucasian face. Slower reaction times indicate weaker associations. Results showing weaker associations between the word “good” and Black faces, as opposed to Caucasian faces, have been argued to indicate an unconscious bias or racial prejudice against Black people. See A. Roberts, (Re)forming the Jury: Detection and Disinfection of Implicit Juror Bias, 44 Conn. L. Rev. 827 (2012). While the IAT’s results are very interesting, researchers disagree about the connection between its results and whether a person racially discriminates. One reason may be that the IAT only measures the negative association, while predicting actual behavior is generally far more complex and multivariate.

Cultural biases are a good example of unconscious bias. Most people are so steeped in their culture that they can’t see the world any other way. There are countless ways in which our culture and subcultures affect our actions, beliefs, attitudes, and decisions, all reinforced by the media and schooling, as well as family and friends. In diverse communities, jury pools will often contain first-generation immigrants who come from cultures where a defendant has the burden of proving their own innocence. Thus, the concept of a prosecutor bearing that burden is foreign and may result in either a juror shifting the burden to the defense or lowering the burden for a prosecutor.

We all have biases—jurors, judges, and lawyers—and they operate in very different ways whether we are conscious of them or not.

When judges or attorneys ask whether a juror can “set aside” a particular experience, belief, attitude, or opinion, it is unclear to us what they mean by this question. Are they asking the juror to act “as if” they don’t have that expressed opinion or the experience? Or is the judge asking the juror to constantly check and correct their conscious or unconscious biases over the course of an entire trial? If a juror has lived with experiences or beliefs about law enforcement, prosecutors, or crime for 20, 30, 40, or 50 years, that becomes their default rules for deciding a case, despite their assurances to the court and the parties that they will only use evidence and law. Even if they are aware of a potential bias, they cannot simply erase it from their brains. They will then use those perceptions to interpret the evidence to conform to those preset beliefs.

Research has shown that information, opinions, etc., are not kept in discrete packets in the brain. They are kept in neural networks. Whenever information comes in, the concept “lights up.” For example, in a white-collar case involving allegations of tax fraud, the evidence of alleged misrepresentation of income on a tax form will light up and get stored. The problem is that all of the associated concepts, such as whether a juror feels they have been unfairly audited, light up as well. Thus, it’s often not possible to eliminate particular thoughts, opinions, etc., in order to act “as if” we don’t have them and correct for their biasing impact.


Biases filter trial information, influence perceptions, and add irrationality into jurors’ decision-making process, often without their awareness. The ABA, certain states, and local jurisdictions have formed committees and task forces to look at the pervasive influence of bias in various aspects of the criminal justice system. Some courts are giving instructions on implicit bias. All of this is promising and illustrates growing awareness of the significance of the problem. Notably, Northern District Judge Mark Bennett in Iowa has been at the forefront of recognizing and instructing on implicit bias.

Do not decide the case based on “implicit biases.” As we discussed in jury selection, everyone, including me, has feelings, assumptions, perceptions, fears, and stereotypes, that is, “implicit biases,” that we may not be aware of. These hidden thoughts can impact what we see and hear, how we remember what we see and hear, and how we make important decisions. Because you are making very important decisions in this case, I strongly encourage you to evaluate the evidence carefully and to resist jumping to conclusions based on personal likes or dislikes, generalizations, gut feelings, prejudices, sympathies, stereotypes, or biases. The law demands that you return a just verdict, based solely on the evidence, your individual evaluation of that evidence, your reason and common sense, and these instructions. Our system of justice is counting on you to render a fair decision based on the evidence, not on biases.

In the Derek Chauvin case, Judge Peter Cahill gave a more refined instruction on implicit biases, which adds some recommendations about how a juror might examine whether they are making a decision based on prior experiences, assumptions, or stereotypes vs. the evidence in the case. See Jury Instructions, Minnesota v. Chauvin, Court File No. 27-CR-20-12646 (2020).

However, the difficulty with jury instructions on implicit bias is the court is instructing jurors to be aware of and correct for something that is unconscious and below their awareness.


The concept of rehabilitation itself is flawed in that it suggests that a judge or attorneys can change a juror’s beliefs. That “set it aside” and “fair and impartial” agreements are commonly referred to as “the magic questions” ironically suggests that there is some mysterious or miraculous cure to preexisting bias. In the treason trial of Aaron Burr over 200 years ago, Chief Justice John Marshall noted the inherent problems with rehabilitation, stating that a biased juror “may declare that notwithstanding [his] prejudices he is determined to listen to the evidence, and be governed by it; but the law will not trust him.” United States v. Burr, 25 Fed. Cas. (D. Va. 1807). In Mattaranz v. State, 133 So. 3d 473 (Fla. 2013), the court stated that it is a “preposterous conclusion that the human capacity for rational reflection is but a light switch that can be flipped on or off, and a trial court may then procure a juror who mere minutes before expressed unacceptable bias and partiality, is suddenly objective and neutral.” In O’Dell v. Miller, 565 S.E.2d 407, 411 (W. Va. 2002), and Montgomery v. Commonwealth, 819 S.W.2d 713, 719 (Ky. 1991), those courts found that the term “rehabilitation” was a misnomer and asked judges to “remove it from their thinking and strike it from their lexicon.” Moreover, questioning should be done “for the purpose of clarification or elaboration” rather than to accomplish the “goal of getting a juror to change a biased attitude.” The New Jersey Judiciary Bench Manual on Jury Selection states, “Once a juror has expressed a concern about an ability to sit on a case because of a prior experience, prejudice, or bias, there is a strong presumption that the judge should simply excuse the juror for cause.”

Rather than considering jurors to be “rehabilitated” if they state they can control something they have no control over or by telling them not to have a given bias, judges and attorneys should engage in a process to better understand the nature of a juror’s relevant experiences and beliefs and their relationship to a given case, how a juror will likely interact with those prior attitudes during the course of a trial, and their estimated skill in their ability to become aware of and correct for those biases. Here is a short set of recommended procedures for judges and attorneys to better evaluate whether a juror can be truly fair and impartial in light of a potential bias. Please note that while these recommended procedures may seem like they will be burdensome and time-consuming for the court, they can actually make jury selection more efficient by focusing the court and counsel on the issues that go directly to cause and peremptory challenges—the ability of jurors to be impartial, given their life experiences and beliefs.

  • In any given case, presume that potential biases will be present.
  • Note that biases are related to a variety of issues that can impair a juror’s ability to be fair and impartial: their prior life experiences, beliefs, opinions, assumptions, values, impressions, assumptions, and personal rules. Biases are not merely demographic categories such as race, gender, or religion.
  • In pretrial conferences, have attorneys identify the biases they are concerned about in their case.
  • Understand that jurors may or may not be aware of their own biases, preferences, or inclinations. Thus, the voir dire process should be about nonjudgmentally discovering with jurors what life experiences or beliefs may affect the way they will listen to a case. Don’t assume they know, and be patient with them.
  • Evaluate the ease or difficulty that jurors will have in disclosing personal experiences or beliefs related to a given case issue (e.g., DUI vs. molestation or sexual abuse, although some jurors may have as much sensitivity to a DUI as others to sexual abuse).
  • Design a supplemental juror questionnaire and/or voir dire questions around the identified bias issues.
  • Whether in a supplemental juror questionnaire or in voir dire, create open-ended questions that encourage jurors to fully disclose their experiences, opinions, or beliefs.
  • Have the judge and each of the attorneys give examples of their own personal biases to create a model for jurors to openly disclose their own. Make these examples of honest and maybe even slightly embarrassing biases as opposed to innocuous biases like sports team or food preferences. If you are not prepared to disclose personal information, how can you expect jurors to disclose their deeply personal information in a sexual assault or homicide case?
  • In voir dire, assume jurors are giving you the least amount of information they can, given the public and intimidating environment of the courtroom. Always ask jurors to elaborate on their initial answers. Liberally use the phrase, “Please tell me more about that . . .” even if you think you know what they mean.
  • Ask about the length, strength, and frequency of a given experience or belief to better understand how it might affect their ability to be fair and impartial. A juror who has recently had a negative experience with the police may have a stronger reaction to law enforcement issues in the case than someone who had an experience 20 years ago.
  • However, some jurors can have a strong emotional charge from a seemingly minor incident that happened years ago. Ask them how the incident affected them to discern the impact of the experience. Ask what conclusions, if any, they have made about that given experience.
  • If a juror has had a number of experiences, it can affect them more profoundly than if they had only one or two incidents. For example, if jurors have had their house robbed, had their car stolen, or been a victim of violent crime on numerous occasions, they are more likely to have stronger opinions about crime and law enforcement.
  • If a juror vocalizes a negative experience related to a case issue or party, they should also be asked what conclusions, opinions, or judgments have drawn from that experience.
  • Always validate the experience or belief that the juror is expressing and thank them for telling you about it. This will communicate to other jurors that the court and counsel truly want jurors to open up and candidly express their experiences and opinions.
  • If the magic “Can you set it aside?” question must be asked, a follow-up question can be asked about how a juror plans to set aside a particular experience or belief. Judges or attorneys can also borrow from the psychological literature on habit formation, specifically, implementation intentions, to create a plan for the juror about how they can remind themselves of the differences between their prior experience or belief and the case issue they are considering.
  • Judges and attorneys should also consider how jurors honestly deal with the concept of their own biases. A juror who too readily and easily agrees they can separate their strong experience from the attendant case may tell the court and parties they will not work at being impartial and thus may be a candidate for a cause challenge.

If done correctly, jury selection procedures, including voir dire, are the process of discovering how a juror’s experiences and beliefs will interact with case issues and parties. These days, jurors have a heightened awareness of social justice, race, gender, politics, religion, and numerous other issues. Social media encourages and reinforces strongly held beliefs and strongly voiced opinions. Judges and attorneys need to better understand the impact of all kinds of relevant biases on a juror’s decision-making process, conduct an open and thorough method for jurors to consider their biases, and grant cause challenges if warranted, in order to provide the parties with their constitutionally guaranteed impartial jury.

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Richard Gabriel is the president of Decision Analysis, Inc., in Los Angeles, California. He is the co-author of Jury Selection: Strategy and Science and has consulted for both the defense and prosecution on the O.J. Simpson, Casey Anthony, Phil Spector, Aaron Hernandez, and other high-profile matters.

John G. McCabe


John G. McCabe, Ph.D. is a cognitive psychologist and senior consultant at Decision Analysis, Inc.

Rebecca C. Ying


Rebecca C. Ying is a forensic psychology M.S. student at California State University, Los Angeles. She is currently an intern at Decision Analysis, Inc.