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Wrongful Conviction Contributing Factors

DNA has changed the criminal justice system forever – but the system has not changed enough.

The exonerations of innocent people have shown that our criminal justice system is fundamentally flawed. DNA exonerations do not solve the problem – they provide scientific proof of its existence, and they illuminate the need for reform.

Over the last 15 years, there has been a major shift in criminal justice legislation as a result of DNA exonerations. Policymakers are increasingly recognizing and addressing the problems these exonerations demonstrate – and they are beginning to enact common-sense reforms that have been proven to improve accuracy in the criminal justice system.

Here are the five major contributing factors to wrongful convictions in order of percent they have been found to contribute to cases of exoneration. Click on each to learn more:  


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1. Perjury or False Accusation

Perjury is known as the offense of willfully telling an untruth in a court after having taken an oath or affirmation. False accusations are when someone knowingly makes a charge of wrongdoing against another person. Perjury claims are usually proven based on a discrepancy between an initial deposition of a witness and their testimony on the stand.


The National Registry of Exonerations has chronicled more than 2,000 cases of wrongful conviction since 1989. In more than half of those cases, perjury and/or false accusations played a role.

There are a number of individuals involved in a case that can be incentivized or coerced into making perjurious statements. This can include witnesses, co-defendants, and victims in cases.


Often, statements from people with incentives to testify- incentives that are not disclosed to the jury—are the central evidence in convicting an innocent person. Those incentivized to testify are often unreliable and untrustworthy.


Many times, those incentivized to testify are jailhouse informants or "snitches". The National Registry defines jailhouse informants as "a witness who was in custody with the exonerated defendant and who testified that the defendant confessed to him." 

Additionally, the Registry notes; "Jailhouse snitch testimony, as it is commonly known, is notoriously unreliable because the incarcerated witnesses are strongly motivated to say what the prosecution wants, usually because they get substantial reductions in their own sentences in return."

According to the Innocence Project, 15 percent of all wrongful convictions later cleared by DNA testing featured false testimony by jailhouse informants. In murder cases, that number is 50 percent.

Reforms in Florida and Beyond 

State and federal governments have recently been examining and improving the law pertaining to guidelines for informant use. These laws are often aimed at improving accountability and reliability of the testimony gathered from informants. 

The reasons informants lie are similar to the reasons why individuals falsely confess; they were coerced, bribed, threatened, lied to, or promised something in return. 

In 2009, Florida passed legislation known as "Rachel's Law" which requires police to advise informants of certain rights and to maintain certain policies with respect to the recruitment and use of informants. 

This law requires that law enforcement provide a person who is requested to serve as a confidential informant with an opportunity to consult with legal counsel upon request before the person agrees to perform any activities as a confidential informant.

It also charges agencies with the responsibility of considering a person’s age and maturity, emotional state and the level of risk an informant would entail. Under this law, police are also barred from promising an informer more lenient treatment; however, judges and prosecutors can still do that.

Click here to see where your state stands in terms of legislation surrounding jailhouse informants. 

Read more about suggested reforms. 


2. Official Misconduct

The National Registry of Exonerations defines Official Misconduct in a wrongful conviction as "police, prosecutors, or other government officials significantly abused their authority or the judicial process in a manner that contributed to the exoneree's conviction." Misconduct can also take place at crime labs. 

As the second leading contributing factor to wrongful convictions, official misconduct appears in many forms. But why do these abuses of power take place? Often times those charged with ensuring truth and justice in the criminal justice system are focused on securing convictions and can lose sight of their greater responsibility to uphold the pillars of justice.


As the Innocence Project writes, "While many law enforcement officers and prosecutors are honest and trustworthy, criminal justice is a human endeavor and the possibility for negligence, misconduct and corruption exists. Even if one officer of every thousand is dishonest, wrongful convictions will continue to occur."

Misconduct and misuse of power happen at all levels of the criminal justice system and are executed by different officials throughout. The most common perpetrators are law enforcement officials and prosecutors. 

Common forms of misconduct by law enforcement officials include:

  • Employing suggestion when conducting identification procedures

  • Coercing false confessions

  • Lying or intentionally misleading jurors about their observations

  • Failing to turn over exculpatory evidence to prosecutors

  • Providing incentives to secure unreliable evidence from informants

Common forms of misconduct by prosecutors include:

  • Withholding exculpatory evidence from defense

  • Deliberately mishandling, mistreating or destroying evidence

  • Allowing witnesses they know or should know are not truthful to testify

  • Pressuring defense witnesses not to testify

  • Relying on fraudulent forensic experts

  • Making misleading arguments that overstate the probative value of testimony

Necessary Oversight 

We need to find solutions to fix these problems. One way to put checks on the enormous power of prosecutors and law enforcement officials would be to establish criminal justice reform commissions to study wrongful convictions and advocate for changes in the system.

Read the Innocence Project's full review of official misconduct here

Read more about reform for this issue. 

Official Misconduct

3. Mistaken Eyewitness Identification

The most common element in all wrongful convictions later overturned by DNA evidence has been eyewitness misidentification. Misleading lineup methods have been used for decades without serious scrutiny. Now is the time for change. 


Mistaken eyewitness identification plays a role in more than 70% of convictions overturned through DNA testing nationwide.

Misidentifications don’t only threaten the innocent, they also derail investigations. While police focus on finding evidence against an innocent person, the perpetrator can get away.


Despite solid and growing proof of the inaccuracy of traditional eyewitness ID procedures – and the availability of simple measures to reform them – traditional eyewitness identifications remain among the most commonly used and compelling evidence brought against criminal defendants.

Most law enforcement agencies use the same methods they have used for decades – live and photo lineups, usually conducted without a blind administrator or proper instructions. It is stressful for victims and eyewitnesses to identify a perpetrator, and they make mistakes.


Sometimes these mistakes are triggered by a gap in memory or the desire to make an identification at all costs. In other cases, subtle cues by police – intentional or not – lead to a false identification. Almost all of these mistakes are preventable.

Read more about eyewitness identification practices here

How Misidentifications Happen

  • In a standard lineup, the lineup administrator typically knows who the suspect is. Research shows that administrators often provide unintentional cues to the eyewitness about which person to pick from the lineup.

  • In a standard lineup, without instructions from the administrator, the eyewitness often assumes that the perpetrator of the crime is one of those presented in the lineup. This often leads to the selection of a person despite doubts.

  • In a standard lineup, the lineup administrator may choose to compose a live or photo lineup where non-suspect “fillers” do not match the witness’s description of the perpetrator. When fillers are selected that do not resemble the witness’s description, this can cause the suspect to stand out to a witness because of the composition of the lineup. This unintentional suggestion can lead an eyewitness to identify a particular individual in a photo array or lineup.

  • In a standard lineup, the lineup administrator may not elicit or document a statement from a witness articulating their level of confidence in an identification made during the identification process. A witness’s confidence can be particularly susceptible to influence by information provided to the witness after the identification process. Research shows that information provided to a witness after an identification suggesting that the witness selected the right person can dramatically, yet artificially, increase the witness’s confidence in the identification. Therefore it is critically important to capture an eyewitness’s level of confidence at the point in time that an identification is made.

These problematic methods can be fixed, and there are a number of proposed methods of reform that will impact the prevalence of this issue. Read more from the Innocence Project here


4. Misapplication of Forensic Science

Misapplication of forensic science is the second most common contributing factor to wrongful convictions, found in nearly half (45%) of DNA exoneration cases.

Misapplication of forensic science casts a wide net that describes a range of issues. This misapplication can happen for a number of reasons; 

  • Unreliable or invalid forensic discipline.

    • Studies have demonstrated that some forensic methods used in criminal investigations cannot consistently produce accurate results.

    • For example, bite mark comparison in which an identification of a biter is made from a bite mark made on skin is an example of an analysis that is unreliable and inaccurate.

  • Insufficient validation of a method.

    • Some of the forensic disciplines in use may be capable of consistently producing accurate results, but there has not been sufficient research to establish validity.

    • Accuracy of a method should be established using large, well-designed studies. Without these studies, the results of an analysis cannot be interpreted. 

    • For example, analysis of shoe prints as a basis of identifying the unique source of a print is an example of a method that has not been sufficiently validated.

  • Misleading testimony.

    • ​Sometimes forensic testimony overstates or exaggerates the significance of similarities between evidence from a crime scene and evidence from an individual (a “suspect” or “person of interest”), or oversimplifies the data.

    • Sometimes forensic testimony fails to include information on the limitations of the methods used in the analysis, such as the method’s error rates and situations in which the method has, and has not, been shown to be valid.

  • Mistakes. 

    • Forensic practitioners can make mistakes, including mixing up samples or contaminating specimens. These can occur in any type of science or laboratory testing, even in well-developed and well-validated fields.

  • Misconduct. 

    • In some cases, forensic analysts have fabricated results, hidden exculpatory evidence, or reported results when testing had not been conducted.

Considerations for Reform

The same concerns were reiterated and expanded upon in the 2016 report, Forensic Science in Criminal Courts: Ensuring Scientific Validity of Feature-Comparison Methods, by the President’s Council of Advisors on Science and Technology (PCAST). 


This report examined the research underlying specific forensic feature comparison disciplines, evaluated their accuracy and reliability, and made recommendations to various federal agencies to strengthen these disciplines. Among the recommendations was the need for better resources to support judicial training given the changing landscape in the evaluation of forensic evidence and state of validation of various forensic techniques.

Read more about ideas for reform that could improve the application of forensic science. 

Additional Concerns

Because shifts in scientific understanding often take decades to emerge, individuals whose wrongful convictions were based on misapplied science might face difficulties in proving their innocence due to time limitations and high evidentiary standards. In addition, some state courts do not recognize discredited scientific evidence as new evidence of a wrongful conviction.

This is why the Innocence Project, as well as IPF, are advocates for access to post-conviction DNA testing.

Read more about the issue of access here.

Read about methods of reform for this issue here




5. False Confessions

More than 1 out of 4 people wrongfully convicted but later exonerated by DNA evidence made a false confession or incriminating statement.

For many reasons – including mental health issues and aggressive law enforcement tactics – innocent people sometimes confess to crimes they did not commit.


While it can be hard to understand why someone would falsely confess to a crime, psychological research has provided some answers – and DNA exonerations have proven that the problem is more widespread than many people think. In more than 25% of the wrongful convictions overturned with DNA evidence, defendants made false confessions, admissions or statements to law enforcement officials.

Researchers who study this phenomenon have determined that the following factors contribute to or cause false confessions:

  • Real or perceived intimidation of the suspect by law enforcement

  • Use of force by law enforcement during the interrogation, or perceived threat of force

  • Compromised reasoning ability of the suspect, due to exhaustion, stress, hunger, substance use, and, in some cases, mental limitations, or limited education. Young people who do not understand their rights and are taught to please authority figures are particularly vulnerable.

  • Devious interrogation techniques, such as untrue statements about the presence of incriminating evidence

  • Fear, on the part of the suspect, that failure to confess will yield a harsher punishment

From the National Registry of Exonerations we learn,


"[The Registry] has collected data on 1,810 exonerations in the United States since 1989 (as of June 7, 2016). They include 227 cases of innocent men and women who confessed, 13 percent of the total, all after receiving Miranda warnings (at least according to the police). Nearly three quarters of those false confessions were in homicide cases.

First, most suspects who falsely confess—probably the great majority—are never convicted at all. In a classic 2004 study, Steven Drizin and Richard Leo identified 125 proven false confessions in the United States from 1971 through 2002. Only about a third were cases of exoneration after conviction. In most, charges were dismissed before trial or never filed at all because of indisputable proof of innocence.


Second, few convictions based on false confessions are cleared by exoneration. That’s true for all wrongful convictions, but especially for those based on confessions. It’s very hard to convince people that a defendant who confessed is innocent. We see this in the cases: Exonerations of defendants who confessed are more likely to depend on the most unassailable evidence, DNA, to overcome the weight of a confession. Forty-two percent of exonerated defendants who had confessed were cleared by DNA tests, compared to only 21 percent of exonerees who had not confessed."

Not only are false confessions common, but once they happen it is nearly impossible to reverse the consequences. Read more from the Innocence Project about false confessions here

Guilty pleas and wrongful or false confessions are related but different. Click here to read more about that distinction. 

Read more about methods to reform for this issue here. 

False Confessions

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