When deciding the guilt or innocence of individuals in court, juries, judges, and police investigators rely on three major types of evidence. Often, experts are relied on for information. For example, the mental state of the individual being accused. This “expert testimony,” is not often relied on in Canadian court because some judges believe the information that is offered by experts, Psychologists in particular, is common sense.
There are other judges, however, that are more concerned with the jurors reliance on the information being provided rather than evaluating information on their own. Researcher A. Daniel Yarmey discovered that several research involving the testing of eyewitness testimony accuracy, including the identification of suspects in line ups, revealed information that has no connection with the knowledge of common sense. Aside from expert testimony, Physical evidence is a second option that experts can use to reach decisions.
Crime scenes are often inspected for evidence such as fingerprints, hair and fibres samples, or footprints. Increasing in accuracy, DNA testing has become a popular choice for obtaining evidence. Nevertheless, through research, it is found that other types of physical evidence are not as persuasive as DNA sampling. At the same time, Statistical evidence is also proven to be unpersuasive. People have a tendency to rely on statistical evidence heavily in certain situations of their everyday lives.
As a result, when jurors, Judges, and police investigators are given the choice of different routes for evidence, they tend to be persuaded by the most unreliable, that is what other people report. Generally speaking, People are often convinced that something is true, when it is confirmed by another.