Credibility

This page was last substantively updated or reviewed January 2017. (Rev. # 95864)

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Introduction

Credibility refers to the trustworthiness of a witness based on their veracity, sincerity and accuracy.

Credibility evidence comprises evidence admitted for the purposes of strengthening or weakening the testimony of a witness or an accused. Credibility evidence that is used to impeach a witness can be submitted at any point from the time the witness takes the stand. The rule is that a witness always puts their credibility at issue whenever they testify and so it is open to attack. Evidence that bolsters a witness's credibility, however, is not admittable until the credibility of that witness has been impeached.

Whenever testimony is given the trier of fact must determine whether the testimony is to be believed. There is no presumption of honesty among witnesses in a criminal trial

There are several approaches to determining credibility. One school of thought believes that credibility is determined primarily by demeanour and conduct in trial. Another approach says that demeanour and conduct are too subjective, and so the best approach is to consider the consistency of testimony when compared to reliable facts.

Consideration can also include:

• ability and opportunity to observe events,
• the firmness of his memory,
• the ability to resist the influence of interest to modify his recollection,
• whether the witness’ evidence harmonizes with independent evidence that has been accepted,
• whether the witness changes his testimony during direct and cross-examination,
• whether the witness’ testimony seems unreasonable, impossible, or unlikely,
• whether a witness has a motive to lie, and
• the demeanour of a witness generally.

As a whole, credibility is a consideration of whether the evidence is "consistent with the probabilities affecting the case as a whole and shown to be in existence at the time."

One recommended approach would follow the formula:

1. consider the testimony on a "stand alone" basis and whether it is "inherently believable";
2. if satisfied, consider the evidence's consistency with other witnesses and documentary evidence. Special consideration should be on those witnesses who are independent;
3. finally, the court should consider which version of events is most consistent with the "preponderance of probabilities which a practical and informed person would readily recognize as reasonable".

Standard of Appellate Review

Findings of credibility are afforded a high degree of deference. This is on account that the trial judge is in a far superior position to assess it.

That being said a material error of law will not be afforded deference, including a assessment on impermissible stereotypical reasoning. A review alleging judge maked an error of law by applying a "stricter standard of scrutiny than the evidence of the Crown" as it relates to evaluating credibility. However, this route of appeal is not be to be used as a "veiled invitation to reassess the trial judge’s credibility determinations."

Oath-helping

It is generally prohibited to adduce any evidence for the sole purpose of bolstering or increasing a witnesses credibility, suggesting they are more likely to be telling truth. Evidence that is adduced for another reason and also has the effect of bolstering credibility can be permitted. The judge must balance the probative value of the evidence against the prejudicial effect. The common law prohibits oath-helping. This rule prohibits evidence that is solely adduced to bolster the witnesses' credibility. Reasons for adducing oath-helping evidence includes showing corroboration with other extrinsic evidence and narrative.

Evidence that is admissible for one purpose and has the tendency to be oath-helping will generally be admitted subject to "appropriate steps to limit the oath-helping nature of the evidence" such as by providing a jury caution.

Exceptions

There are two exceptions where oath-helping is permitted. First, it does not apply when the accused testifies. In those circumstances, the accused has "wide latitude" to present oath-helping and character evidence. Second, oath-helping is permitted to bolster the credibility of a witness whose credibility has been attacked. The scope however is limited.

Examples

The Crown cannot introduce evidence showing that their witness has testified in court previously resulting in convictions.

The Defence cannot adduce evidence establishing that the accused passed a polygraph test.

Failure to Call Witnesses

In certain circumstances, adverse inferences may be made from a party's failure to call a witness. Any inference should be made from "ordinary logic and experience" and only where there is "plausible reason for nonproduction."

There are many circumstances where there is reason not to call a witness that is unrelated to honesty, such as due to overlap with other witnesses, poor demeanor, or limited relevancy. However, a negative inference is more likely drawn where the witness is able to provide "missing proof" that would be important to the case.

It is dangerous to draw an adverse inference from the failure of the accused to call evidence. A judge should only draw an adverse inference be done "with the greatest of caution."

Topics

• Collateral Fact Rule
• Bias, Interest, and Corruption
• Prior Consistent Statements
• Prior Inconsistent Statements
• Adverse and Hostile Witnesses
• Post-Offence Conduct
• Criminal Record
• Complainant's Sexual Activity Evidence
• Disreputable and Unsavoury Witnesses
• Analyzing Testimony

See Also

• Examinations
• Character Evidence