What to Know About Wrongful Convictions

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“There are a variety of ways to address the issues that lead to wrongful conviction. But at the core, the most fundamental fact of wrongful conviction is this is a complicated phenomenon, as both intentional and unintentional errors are contributing to it.”Shi Yan, PhD, Assistant Professor at the School of Criminology and Criminal Justice, Arizona State University (ASU)

The advent of DNA evidence in the late 1980s heralded a new era for overturning wrongful convictions. At the same time, it began to reveal just how widespread wrongful conviction has been in America. The National Registry of Exonerations (NRE) has recorded over 3,175 overturned wrongful convictions since 1989, and over 27,200 years of freedom have been lost for those who served sentences for crimes they did not commit. Those are only the cases of which we know.

The contributing factors to wrongful convictions are myriad, and it is as much a mistake to blame misconduct and negligence solely as it is to deny the problem altogether. But both forensics and criminal justice professionals can play a powerful role in reducing wrongful convictions and making a safer, more equitable system for all.

Read on to learn more about the causes of wrongful convictions and how they might be mitigated in the future.

Meet the Expert: Shi Yan, PhD

Shi Yan

Dr. Shi Yan is an assistant professor at the School of Criminology and Criminal Justice, Arizona State University (ASU). He is also an affiliated faculty of the Law and Behavioral Science group at ASU. Dr. Yan received both his MA and his PhD. in criminal justice from the University at Albany, SUNY.

Dr. Yan’s research pursues a better understanding of the contemporary American court system, with two focal areas. He studies the correlates of guilty pleas, including false guilty pleas, with both experiments and analyses of quantitative court record data. He also studies how prior criminal records and other factors shape the image of risk in the criminal justice context, and how the perceived risk further relates to case outcomes. His studies have been published in leading academic journals in criminology, law and psychology, and other disciplines. His research has received funding from the National Institute of Justice, the National Science Foundation, and state and local agencies in Arizona.

Understanding the Causes of Wrongful Conviction

In the US, convictions occur in two main ways: a defendant can be found guilty by trial or waive their right to trial and plead guilty. Historically, most of the public’s attention has focused on wrongful convictions stemming from trial convictions. But each category has its own share of wrongful convictions.

“Wrongful conviction at trial has a number of contributing factors,” Dr. Yan says. “Sometimes wrongful convictions are the result of intentional acts, such as false accusations or a key witness lying. Others may be related to errors people make unintentionally.”

A common cause of wrongful conviction at trial is eyewitness misidentification. That misidentification could be willful, but it could also be because the eyewitness was either misled or mistaken. Lineup examinations, in which witnesses are presented with a group of individuals and asked to identify the perpetrator of the witnessed crime, are an essential tool of the criminal justice system, but not perfect. Similarly imperfect is the human memory, especially as the time between a witnessed event and its corresponding trial increases.

“Another potential factor is false confessions,” Dr. Yan says. “A person may admit that they have done something when they have actually not done that. There are a host of psychological factors behind why that might be happening. In the past, there has been a wide and firm belief that if a person admits doing something, it must be true. But with the studies on memory errors and false confessions advancing, people are realizing that even confessions and admissions might be wrong.”

Wrongful convictions can also stem from the conduct of investigators and prosecutors. While this can, in some cases, be intentional—such as withholding evidence that appears to favor a defendant—it is more likely to stem from confirmation bias and tunnel vision.

“Tunnel vision is when the prosecutor or investigating officers get too fixated on pieces of evidence that are pointing to a particular defendant being guilty,” Dr. Yan says. “And that fixation can make them unintentionally unaware of pieces of evidence that are going the other way.”

Wrongful convictions that stem from a guilty plea come with some unique contributing factors and considerations, but they are no less important. In the US, over 95 percent of all convictions result from a guilty plea, and people do plead guilty to crimes they did not commit. It’s not uncommon for prosecutors to present defendants with a sentence they’ll recommend if the defendant pleads guilty, and compare it with a much harsher sentence they’ll pursue if the case goes to trial. In less serious crimes, the prosecutor may offer a sentence that spares the defendant from incarceration in exchange for a guilty plea.

“Some defendants may decide pleading guilty is in their best interest, because they don’t want to risk the harsher sentence at trial,” Dr. Yan says. “Another scenario, for individuals who have committed a relatively less serious crime, is they may be detained in jail before the trial, and then as part of a guilty plea agreement, the prosecutor may sentence them to time served, so they can be immediately released if they accept the deal. Some individuals choose to admit guilt and get out.”

The Impact of DNA Testing on Wrongful Convictions

DNA evidence has played a crucial role in exoneration in many of the most well-known wrongful conviction cases. First used in a criminal investigation in 1987, DNA profiling has not only impacted investigations after that date but also has been used retroactively in past cases where wrongful conviction claims have been made. The justice system is stronger for it: conclusive DNA evidence is practically irrefutable compared to the fractured memory of a single person.

“One of the biggest advantages of DNA evidence is everyone’s DNA is unique,” Dr. Yan says. “It has strong proving power in both directions: either linking someone to a crime or disconnecting them from a crime.”

According to the National Registry of Exonerations (NRE), approximately one in five exonerations have involved DNA evidence. That’s a highly significant figure, but not an overwhelming one, and DNA evidence isn’t a catchall solution to wrongful convictions. Some crimes simply don’t have DNA evidence. Resources for DNA collection and analysis are not infinite, which can result in significant delays in the presentation of DNA evidence for investigators. And DNA evidence can, like all other evidence, be mishandled by humans, who are still vulnerable to issues like tunnel vision or confirmation bias.

Addressing Wrongful Conviction

“There are a variety of ways to address the issues that lead to wrongful conviction,” Dr. Yan says. “But at the core, the most fundamental fact of wrongful conviction is this is a complicated phenomenon, as both intentional and unintentional errors are contributing to it.”

Dr. Yan separates the methods of addressing wrongful conviction into two areas of interest: the science and technology side, and the law and policy side. The science and technology side includes issues within investigation and trial, such as DNA evidence, confirmation bias, and eyewitness misidentification. The law and policy side focuses on how statutes and case laws either do or do not contribute to preventing wrongful conviction, such as the rules regulating interrogation, the exchange and presentation of evidence, and the admissibility of evidence.

“It would be helpful if new and aspiring criminal justice professionals were willing and able to cross intellectual borders,” Dr. Yan says. “To learn about both the law and the science.”

Elements of coordination between the two sides are already underway. Prosecutors are becoming increasingly aware of the underlying issues around wrongful conviction, and some have taken initiatives within their offices to combat them. These can take the form of conviction integrity units (CIUs) or conviction review units (CRUs), which serve as a sort of internal quality control branch for cases the office is currently handling and those it’s handled in the past. As of 2022, only 95 CIUs operate out of more than 2,300 prosecutor offices nationwide. Those CIUs, either alone or in cooperation with other groups, helped secure 60 percent of exonerations reported in the previous year (NRE 2022).

“Criminal justice professionals can contribute to the reduction of wrongful convictions on the prosecutor’s side in two ways,” Dr. Yan says. “One is to join a prosecutor’s office and help improve the quality of cases, particularly when there is a standalone conviction review or integrity unit. The other is to participate in local prosecutor elections, and help elect prosecutors who prioritize integrity and are receptive to new developments in science.”

The Future of Wrongful Convictions

Wrongful conviction was not widely studied or talked about until the early 2000s or late 1990s, but today it enjoys more scholarly and policy attention than ever before. The number of exonerations remains in a clear uptrend. But whether this is a problem that’s getting better or worse is notoriously difficult to track: knowing precisely how many wrongful convictions there are is an inherent part of the problem of wrongful convictions.

However, the continued advancement of science and technology holds promise for reducing wrongful convictions. Better DNA analysis will be able to find conclusive results where previously only inconclusive results were possible. The proliferation of surveillance cameras in public places can often replace the spotty memory of eyewitnesses. And an increasing number of police departments adopting body cameras can also create a more objective body of evidence for investigators and trial participants. But all evidence, no matter how objective, still needs to be handled and judged by people, leaving it vulnerable to confirmation bias, tunnel vision, and other cognitive processes.

“I’m cautiously optimistic about the future of efforts addressing wrongful convictions,” Dr. Yan says. “There is a stronger awareness in society in general. But there’s still work to do.”

Additional Resources on Wrongful Conviction

If you’re interested in learning more about wrongful convictions, and how you can help advocate for those affected, check out some of the resources below.


Matt Zbrog

Matt Zbrog is a writer and researcher from Southern California. Since 2018, he’s written extensively about the increasing digitization of investigations, the growing importance of forensic science, and emerging areas of investigative practice like open source intelligence (OSINT) and blockchain forensics. His writing and research are focused on learning from those who know the subject best, including leaders and subject matter specialists from the Association of Certified Fraud Examiners (ACFE) and the American Academy of Forensic Science (AAFS). As part of the Big Employers in Forensics series, Matt has conducted detailed interviews with forensic experts at the ATF, DEA, FBI, and NCIS.