You probably been taught that our justice system uses the notion that person is ‘innocent until proven guilty’. As Americans, we pride ourselves on our commitment to justice. However, as technology has improved in forensic science, people have begun to realize that our system is more flawed than we hoped.
People are wrongfully imprisoned – even wrongfully put on death row – at astounding rates, which strips innocent people of their basic human rights – freedom, autonomy, dignity. Over 400 people have been exonerated by proving their innocence through DNA testing.
You may wonder why so many people are wrongfully imprisoned. Here are a few of the most common causes.
Causes of Wrongful Imprisonment
Eyewitness misidentification is the single greatest cause of wrongful convictions nationwide, playing a role in more than 75% of convictions overturned through DNA testing.
Unreliable or Limited Science
The arrival of DNA evidence in American courtrooms in the late 1980s and 1990s changed the criminal justice system forever. The widely accepted strength of DNA testing has led experts to call into question the reliability of other forms of forensics. Where these older forms of forensic science could indicate that someone might have committed a crime, DNA can show whether someone is actually guilty or innocent.
In more than 25% of DNA exoneration cases, innocent defendants made incriminating statements, delivered outright confessions or pled guilty.
These cases show that confessions are not always prompted by internal knowledge or actual guilt, but are sometimes motivated by external influences.
Forensic Science Fraud or Misconduct
Because forensic science results can mean the difference between life and death in many cases, fraud and other types of misconduct in the field are particularly troubling. False testimony, exaggerated statistics and laboratory fraud have led to wrongful conviction in several states.
Since forensic evidence is offered by "experts," jurors routinely give it much more weight than other evidence. But when misconduct occurs, the weight is misplaced. In some instances, labs or their personnel are too closely tied to police and prosecutors, and cannot therefore be considered impartial. Other times, a criminalist lacking the requisite knowledge embellishes findings, confident that he will not be caught since the lawyer, judge, and jury have no background in the relevant science.
Some wrongful convictions are caused by honest mistakes. In some cases, however, officials take steps to ensure that a defendant is convicted despite weak evidence or even clear proof of innocence.
The cases of wrongful convictions uncovered by DNA testing are replete with evidence of fraud or misconduct by prosecutors or police departments.
Informants or Snitches
In more than 15% of cases of wrongful conviction overturned by DNA testing, an informant or "jailhouse snitch" testified against the defendant. Often, statements from people with incentives to testify – particularly incentives that are not disclosed to the jury – are the central evidence in convicting an innocent person.
The resources of the justice system are often stacked against poor defendants. Matters only become worse when a person is represented by an ineffective, incompetent or overburdened defense lawyer. The failure of overworked lawyers to investigate properly, call witnesses or prepare for trial has led to the conviction of innocent people. When a defense lawyer doesn't do his or her job, the defendant suffers. Shrinking funds and limited access to resources for public defenders and court-appointed attorneys is only making the problem worse.
This list does not cover all the cases, nor does it cover all the causes for wrongful imprisonment. In many circumstances, combinations of many such causes resulted in the mistakes.
Below is a chart from The Innocence Project summarizing the largest factors of wrongful imprisonment based on data from the first 130 DNA exonerations.