It is safe to say that this might be one of the issues where there is unanimity among judges with concern about implicit bias in the justice system. I will confess I have no solution, but I thought I’d share some thoughts developed for a talk I am giving.
Former Federal Judge Mark Bennet has an interesting implicit bias instruction:
Growing scientific research indicates each one of us has “implicit biases,” or hidden feelings, perceptions, fears, and stereotypes in our subconscious. These hidden thoughts often impact how we remember what we see and hear and how we make important decisions. While it is difficult to control one’s subconscious thoughts, being aware of these hidden biases can help counteract them. As a result, I ask you to recognize that all of us may be affected by implicit biases in the decisions that we make. Because you are making very important decisions in this case, I strongly encourage you to critically evaluate the evidence and resist any urge to reach a verdict influenced by stereotypes, generalizations, or implicit biases.
Determining credibility is among the most difficult things judges and jurors do. Judges regularly make credibility determinations. But before you think with practice judges get better at this there are studies which found that judges are not necessarily better than others at figuring out who is telling the truth. For example, in a controlled study of 110 judges with an average of 11.5 years on the bench, judges did not do better than chance in telling who was being truthful and who was not. See Paul Ekman & Maureen O’Sullivan, Who Can Catch a Liar?, 46 Am. Psychologist 913 (1991); Richard Schauffler & Kevin S. Burke, Who Are You Going to Believe?, 49 Court Rev. 124 (2013). Judge Learned Hand once said, “The spirit of liberty is the spirit which is not too sure that it is right.”
If judges are the “experienced pros” at determining credibility what about jurors? Minnesota’s pattern jury instructions say that jurors should consider the manner in which a witness testifies. See Minnesota CIVJIG 12.15 Evaluation of Testimony–Credibility of Witnesses – Guidelines for evaluating testimony and Minnesota CRIMJIG 3.12 Evaluation of Testimony — Believability of Witnesses. Most states have something similar to Minnesota’s jury instruction. Telling jurors to consider the manner of a witness may well be appropriate, but is it possible that we unintentionally invite jurors to decide credibility based upon implicit bias as a result of this part of the instruction? Perhaps we can learn from New Zealand.
The New Zealand Supreme Court said:
[R]esearch which indicates that a person’s demeanour when giving evidence in court generally provides little or no assistance to a fact-finder charged with determining whether or not the witness is telling the truth. A witness who presents as confident, articulate and honest may be mistaken or dishonest; a witness who presents as diffident, hesitant or awkward may be telling the truth and their evidence may be accurate. Not only can appearances be deceptive, but fact-finders may over-estimate their ability to recognise those who are truthful from those who are not, by, for example, relying on unreliable behaviours such as fidgeting or looking away.
Taniwha v. The Queen  NZSC, September 8, 2016.
New Zealand’s suggested Jury Instruction:
I must warn you, though, that simply observing witnesses and watching their demeanour as they give evidence is not a good way to assess the truth or falsity of their evidence. For example, a witness may not appear confident or may hesitate, fidget or look away when giving evidence. That doesn’t necessarily mean that their evidence is untruthful. The witness may be understandably nervous giving evidence in an unfamiliar environment in front of unknown people. Or there may be cultural reasons for the way a witness presents. On the other hand, a witness may appear confident, open and persuasive but nevertheless be untruthful. And remember that even an honest witness can be mistaken.
Things like gestures or tone of voice may sometimes help you to understand what the witness actually means. But you should be cautious about thinking that they will help you much in determining whether or not the witness is telling the truth.