In the USA, why are witnesses who demonstrated prejudice and bias not immediately removed and disqualified?
<p>I just saw the witness examination of the George Floyd case. The 18 year old female witness went on to ramble about how she felt so sorry for Floyd and that her father and brothers are all black just like Floyd.</p>
<p>Any reasonable person would agree that she is prejudiced and biased.</p>
<p>So then, what is the theory that justifies allowing prejudiced and biased witnesses to testify?</p>
<p>After all, prejudiced and biased citizens are not allow to serve as jurors.</p>

<h2>Prejudice and bias goes to credibility</h2>
<p>The trier of fact has to decide how much weight to give each piece of evidence including witness testimony. A clearly prejudiced or biased witness will, all else being equal, deserve less weight than a more unbiased or less prejudiced witness.</p>
<p>Or, at least, one who is less <em>obviously</em> biased and prejudiced - because everyone is biased and prejudiced. A witness who clearly and unequivocally declared their bias and prejudice probably deserves more credit than one who reveals it unwillingly during examination.</p>
<p>The witnesses you use are the people who were there - you don’t get to choose their character.</p>

<p>Prejudiced and biased witnesses can be allowed because there are protections in place to prevent their bias and prejudice from negatively affecting the case getting a correct outcome. Consider:</p>
<ol>
<li><p>The jurors can hear what the witness says and make up their own minds about whether the witness is biased or prejudiced. One might expect reasonable jurors to give less weight to witnesses who are obviously biased or prejudiced. Jurors with bias or prejudice can make decisions that affect the outcome of the case without ever having to reveal their personal biases or prejudices.</p>
</li>
<li><p>The defense gets to cross-examine biased or prejudiced witnesses and, provided the questions are reasonable, the witness can be required to provide an answer, even when the witness might prefer not to do so. Nobody gets to question the jurors and if the jurors make a bad decision on the basis of bias or prejudice, that decision stands and there's nothing the prosecution can do about it.</p>
</li>
<li><p>If the bias or prejudice causes the witness to perjure himself or refuse to comply with the orders of the judge, the witness can be held criminally liable or in contempt of court and punished accordingly. Jurors can make their decision for any reason at all and simply refuse to disclose the true reasons for those decisions. There is nothing the court can do about a juror's decision based on personal biases or prejudices that the juror does not disclose.</p>
</li>
</ol>
<p>These are some considerations which may help explain why the prosecution and defense might want to exclude jurors who are biased one way or the other - biased jurors, once selected, are basically free to exercise their bias without any repercussions whatever (at least, if they keep their biases or the influence of those biases on their decisions somewhat discreet).</p>

united-states witnesses jurisprudence