common-law witnesses impeachment
Is there presumption of lack of witness&#39; credibility?
<p>Can a party in a case ever argue that their opponents' lay witness lacks credibility just because there is no evidence of their credibility?</p>
<p>Where the judge is the trier of fact (judge-alone/bench trials), can they assert that a witness is not to be trusted simply as there is no evidence of their character?</p>
<p>To avoid doubt, there is no evidence discrediting the witness.</p>
<p>(Any common law jurisdiction).</p>
<h3>Background to the question</h3>
<p>Unlike the police, private prosecutors cannot access criminal history of their witnesses to disclose to the defence. The defence, having been used to be given criminal histories of prosecution witnesses, questions credibility of the private prosecutor's witnesses and challenges the prosecutor to ask the witnesses to disclose their criminal histories voluntarily. The judge says that refusal to do so <em>may</em> be seen as a doubt of credibility of the witnesses. I say that is arguable, to which the judge agrees. It is unclear how this would be ultimately resolved.</p>

<p>A lawyer for either party can claim, during argument, that an adverse witness is not credible, for any reason or none. Often the lawyer will point to matters disclosed during cross-examination, claiming that they are contradictions, show bias, or otherwise indicate lack of credibility. Or the lawyer could point to elements of the primary testimony which the lawyer claims are implausible. If there has be evidence of a prior conviction, the lawyer could refer to this.  A lawyer may in general ask a witness about prior convictions.</p>
<p>Criminal convictions are generally matters of public record, and can be researched.</p>
<p>It is not usual to present reputation or credibility witnesses for any person except the defendant, and failure to do so, even for the defendant, does not lead to any automatic assumption of lack of credibility.  Not does the appearance of such a witness grant an automatic assumption of credibility. But a lawyer may point out reasons for thinking a witness not credible.</p>
<p>Ultimately it is up to the finder of fact, often a jury, to decide what weight to give the testimony of each and every witness, based on the impression that testimony made, as well as any argument from the lawyer.  This is one reason why courts are reluctant to overturn factual assessments by a jury: the reviewing court does not see and hear the manner of a witness and what it may indicate about credibility.</p>

<p>If anything, the opposite. A witness under oath is assumed to be testifying truthfully in the absence of evidence to the contrary. A jury, of course, is free to weigh the credibility of a witness in any manner desired.</p>
