Variables affecting reliability of Testimony
Wrongful convictions can occur in a variety of situations and for a range of crimes.
Witnessing someone steal from a store is not the same as witnessing someone physically assault another person, and being a victim of a handbag snatch is not the same as being a victim of rape. While the results of one study may not be applicable to other crime scenarios, they do provide useful information to the judicial system. The findings of the research have also revealed measures to improve the credibility of witness evidence in both the police station and the courtroom.
System variables are those that can influence eyewitness testimony and are under the criminal justice system's control. The manner in which the police interrogate a witness and the processes for requesting a witness to identify a perpetrator in an identification parade are both system variables.
Estimator variables are those that may have an impact on eyewitness testimony but are beyond the criminal justice system's control. This can include factors like whether the culprit was disguised or was too far away from the witness to be accurately identified. These are clear factors that neither the police nor the courts can influence.
Although research on estimator variables cannot be used to change the processes used in investigations and trials, the findings can be used to determine how likely the witness is to deliver trustworthy evidence.
Another thing to keep in mind when studying psychology and the law is that the law and various systems of justice differ from country to country.
The legal system in the United Kingdom, as well as other nations that have adopted the English common law system, is classified as adversarial or accusatorial.