Criminal prosecutions in Indiana often rely on eyewitness testimony to pursue convictions against defendants. However, there are significant limitations to eyewitness testimony that make it problematic. Here’s why eyewitness testimony is unreliable in legal proceedings.
What is eyewitness testimony?
Eyewitness testimony in the context of the criminal justice system refers to any report offered in court by someone who has observed an event that they witnessed that’s relevant in some way to a criminal case. It’s always delivered formally under oath, so the witness is bound by the law to tell the truth under penalty of perjury, the technical term for lying to the court.
Why is eyewitness testimony unreliable?
When presented with eyewitness testimony, criminal defense must demonstrate why it’s not as reliable as it might seem at face value.
First of all, it’s important to understand that inaccurate eyewitness testimony is often one of the main forms of evidence that prosecutors use to make their cases.
But not all eyewitness testimony can be trusted. There are three factors called estimator variables that can affect the veracity of eyewitnesses’ testimony.
Three estimator variables affecting eyewitness testimony accuracy
The three estimator variables that affect eyewitness testimony accuracy are:
- Situational variables, which refers to the environmental conditions at the time of the observation, such as weather conditions and lighting
- Target variables, which refers to what characteristics of the “target” (the individual under scrutiny) that the eyewitness perceived, such as height or weight
- Witness variables, which refers to the characteristic of the witness that might affect their capacity to make an accurate assessment, such as eyesight or mental competence
Human perception is limited by the environment and is also subjective. There is no foolproof way for investigators to compensate and correct for these confounding variables, so they are inherent to some degree in all eyewitness testimony. It’s up to the criminal defense lawyer to raise these issues on behalf of their client.
Criminal defense relies on undermining any eyewitness testimony that might implicate the client, which includes, for example, calling into question witness credibility and the likelihood that the observation was accurate based on lighting conditions or other situational variables.
There is another category of variables called system variables that can interact with estimator variables. These can and should be corrected in the legal system to better ensure the integrity of the criminal justice process and protect the rights of defendants.