By Kelly Lawson
This is a second response to "Now you see it, now you don't".
Dr. Vallano makes several excellent points. Allow me to play prosecution advocate for a moment. I completely agree that memory is fallible (and malleable). I also completely agree that attorneys and judges need to be aware of the potential issues with eyewitness identification. However, when experts are presented to the jurors, how do they use this information? Does the knowledge that the presence of a weapon may impair identification lead jurors to completely dismiss the eyewitness? As Dr. Vallano pointed out, not all witnesses are inaccurate. How do we safeguard against the discrediting of an accurate witness?
While we do have an estimate of the number of wrongful convictions in which faulty eyewitness testimony played some role (75%), it is unclear how many cases rely solely on eyewitness testimony. The simple fact is – not all cases have pristine traces of DNA. We need those eyewitnesses. However, would it be prudent to present testimony that may harm these cases? Are we letting ten guilty go free to prevent one wrongful conviction?
Psychologists have sought to answer this question. In one study, Cutler, Dexter and Penrod (1989) found jurors can adequately use expert testimony. It does not lead the complete skepticism and discrediting of the eyewitness. Jurors are able to weigh the testimony presented in light of any factors that could have led to inaccuracy. Later studies have also produced similar findings. Yes, it is possible that accurate witnesses may be discredited. However, the impact is not as detrimental as some judges would like to think.
In the Commonwealth v Walker case described by Matt Mangino, there were several factors that could have impacted the identification. It is one thing to know that poor lighting could affect a witness or that it may be difficult to identify a person of a different race. But it is completely another to have the experts state just how much these factors can affect eyewitness accuracy. That quanitative impact is important. In other words, how much do these factors affect accuracy? Do they reduce accuracy by 10%? 60%?
At the end of the day, no one wants to know that a guilty person was set free. Before that expert gets to the courtroom to educate the jury by providing “helpful” information, it would behoove law enforcement to follow recommended procedures. We cannot control the lighting at the time of the crime nor the perpetrator’s race (referred to as estimator variables by Wells, 1978 ) but we can control how the witnesses are interviewed and how they make identifications (referred to as system variables by Wells, 1978). That means that when the eyewitness expert testifies that the chances of mistaken witness are 1.56 times greater when the perpetrator is of a different race, the expert can also highlight the fact that the police administered a blind, sequential lineup without the use of any suggestive instructions. And yes, correct identifications decrease in these situations. But which do you prefer? The ten guilty going free? Or that one innocent person on death row?
Kelly Lawson is a trial consultant and instructor based in Miami, Florida.