There are multiple issues with police lineups that shouldn’t be ignored. Although this method of identifying suspects has proven a superior alternative to show-ups, they’re still full of potential problems in Missouri and the rest of the U.S. Many of these issues are directly tied to the biases of the witnesses and investigators.
Proper lineup construction is key
The degree to which the results of a lineup might be biased depends greatly on how the lineup is constructed and if all the necessary precautions are taken. One of the most important bias safeguards is to keep the investigators out of the field of vision of the witnesses. Otherwise, it’s all too easy for them to intuit which individual they have their focus on. This may lead them to a decision based on what they feel they’re supposed to say, rather than their own memory of the crime they saw.
In a perfect world, investigators wouldn’t even be aware of which individual in the lineup is the actual suspect. That’s what would be necessary for a true double-blind procedure, which is what’s recommended for a police lineup.
But that’s rarely the way it works out in real-life criminal defense. Inevitably, the investigator will look more closely at the suspect than any of the foils in the lineup, and it’s quite easy for witnesses to pick up on those barely perceptible social cues.
Everyone in the lineup should be comparably photographed and dressed
There may also be biases in how the suspect is photographed for the lineup. Lineups aren’t usually conducted in person with everyone standing in a line. More often, photographs are used instead. How a person is dressed and the lighting in the picture can make a substantial difference in the witness’s impression.
When a police lineup is set up properly and under ideal circumstances, it is a highly effective way of identifying suspects. Unfortunately, lineups aren’t always put together the way they should, and some inherent biases are hard to avoid.