How does the law guarantee true disregard by jurors?
<p>How can the court and public guarantee disregard by jurors when they're instructed to do so? I doubt that a verbal instruction suffices, when judges themselves can be biased. What forestalls or thwarts such potential subconscious regard or bias?</p>

<p>Source: Richard A. Posner, <em>How Judges Think</em> (2008), <a href="https://books.google.com/books?id=ZVUC8riEVPQC&amp;lpg=PA9&amp;ots=4VU2mLBny2&amp;dq=%22criminal%20defendants%20are%20at%20a%20disadvantage%22&amp;pg=PA9#v=onepage&amp;q=%22criminal%20defendants%20are%20at%20a%20disadvantage%22&amp;f=false" rel="nofollow noreferrer">p. 9 Top</a>.</p>

<blockquote>
  <p>Criminal 
  defendants are at a disadvantage if a judge's or prosecutor's missteps can 
  be forgiven by the judge's telling the jury to disregard them, for the bell 
  cannot be unrung; the jurors cannot exclude what they should not have 
  heard from their consideration of the defendant's guilt. </p>
</blockquote>

<p>You can't guarantee a juror's disregard, and some attorneys might utilize the "once it's said, it can't be unsaid" strategy because they know that the jury will still keep it in the back of their mind even though they've been told to ignore it. But there are checks and balances to prevent a remark having an impact on the final decision:</p>

<ul>
<li><p><strong>Jury deliberation.</strong> Chances are, not all jurors will keep the thought in their mind. The jury gets a chance to deliberate after the case has been presented, and it's very easy for other jurors in the deliberation room to point out they're ignoring that piece of information and not let it influence the final decision.</p></li>
<li><p><strong>Declaring a mistrial.</strong> A mistrial is fully at the judge's discretion, but generally anything that affects the jury's ability to remain impartial can result in a mistrial being declared (for example, if an attorney deliberately said something outrageous to influence the jury when they knew it would be withdrawn, the judge will likely declare a mistrial without much thought). Once a mistrial is declared, the case will be postponed and a brand new jury will be selected that hasn't heard the previous remarks - easiest way to erase it from their minds is to not use their minds.        </p></li>
</ul>

trial jury