Postconviction DNA analysis

DEFINITION: Examination of DNA evidence in criminal cases that have already concluded with conviction of the accused.

SIGNIFICANCE: The findings of postconviction DNA analysis can serve to affirm correct convictions, exonerate persons who have been wrongfully convicted, and identify the true perpetrators of crimes for which others were convicted. Such DNA analysis thus plays a vital role in maintaining the integrity of the criminal justice system.

The introduction of (deoxyribonucleic acid) analysis revolutionized forensic science and provided law-enforcement agencies with a powerful tool for solving crimes. The proper use of DNA analysis can identify individuals with a higher degree of confidence than is possible with other forensic techniques, and such analysis has led to the conviction of many criminal offenders. Equally important, postconviction DNA analysis has resulted in the exoneration of many persons who had been wrongfully convicted of crimes. Postconviction analysis of DNA evidence may be conducted because access to such analysis was unavailable during the convicted offender’s earlier trial or because advances in analysis techniques since the individual was convicted may provide better evidence than was available at the time of the trial.

Background

As a tool of forensic science, DNA analysis has a relatively short history. It began in 1985 in Great Britain, when Alec Jeffreys, a geneticist, stumbled onto the use of DNA markers (restriction fragment length polymorphisms, or RFLPs) for personal identification while searching for disease markers in human DNA. He saw the potential for the method’s use in criminal and civil investigations and coined the term “DNA fingerprinting,” later explaining that he chose the term in a “deliberate move to emphasize the new forensic paradigm” that he foresaw. In April, 1985, Jeffreys was asked by Britain’s Home Office to use to solve an immigration dispute regarding the family identity of a boy. Although the blood group evidence supported the boy’s claim of true kinship with the family, it was not convincing. The findings of the DNA analysis performed by Jeffreys and his colleagues supported the authenticity of the boy’s claim.

The publicity that accompanied this case not only opened a floodgate of inquiries from immigrant communities over previously disputed cases but also led to the introduction of the use of DNA fingerprinting in paternity tests and many other applications. By 1986, the terms “DNA profiling” and “DNA typing” were also being used to refer to the technique. In the same year, saw its forensic debut in a case in Leicester, Jeffreys’s hometown. This first admission of DNA typing evidence in a criminal court led to the exoneration of a young man who had falsely confessed to and murder. After that trial, the first-ever DNA-based manhunt subsequently brought the true perpetrator to justice; he was convicted in 1987. In the decades that followed, DNA typing became a standard tool of forensic science.

Postconviction Exonerations

The power of DNA evidence to solve crimes and convict perpetrators is widely known, but the general public is perhaps less aware of the potential of such evidence to free wrongfully convicted individuals. The first person in the United States whose criminal conviction was overturned as the result of DNA evidence was a Chicago man named Gary Dotson. He was convicted in 1981 of a rape that never occurred and exonerated in 1989. The purported rape victim had recanted her in 1985, but it was not until 1988 that DNA analysis positively excluded Dotson as the source of found on his accuser (the semen was that of the young woman’s boyfriend, with whom she had consensual sex the day she claimed to have been raped). In 1993, Kirk Bloodsworth became the first person in the United States to escape a death sentence as the result of DNA analysis; he had been convicted of the 1984 rape and murder of a child, but postconviction DNA analysis proved that semen found on the victim was not his. The true perpetrator of the crime was eventually identified in 2003, also with the aid of DNA analysis.

In 2023, Leonard Mack, a 72-year-old Black man, was officially exonerated of rape 47 years after being found guilty. Mack was pulled over by police in 1975 in Greenburgh, New York, after two teenage girls were stopped while walking home from school and one of them was violently raped. The other teen managed to get free and ran to a nearby school, where a teacher called the police. The girl described the suspect as a Black male in his early twenties. Mack had been driving through the neighborhood at the time and was taken to the police station even though he had an alibi. He was then wrongfully identified in a lineup. During the trial, prosecutors presented flawed evidence and ignored a medical examiner's finding that crime scene evidence indicated Mack was not a match. Mack served more than seven years in prison. Investigators identified a convicted sex offender after running his DNA through a database. The man later confessed to the crime.

Using postconviction DNA analysis to exonerate persons who have been wrongfully convicted is the central mission of the Innocence Project, an organization founded in 1992 by Barry Scheck and Peter Neufeld at the Benjamin N. Cardozo School of Law at Yeshiva University. The Innocence Project provides legal assistance to prisoners who could be proven innocent through DNA analysis, and it also works to publicize the fact that wrongful convictions are not rare and isolated incidents but instead the predictable results of defects in the criminal justice system. By 2020, the Innocence Project had documented the exoneration of 375 individuals, with 21 of them having been sentenced to death row. Beyond simply freeing innocent people who are incarcerated, the Innocence Project attempts to reform the system that is responsible for their unjust imprisonment.

Regulations Governing Postconviction DNA Testing

Although thirty-eight US states have laws in place that allow convicts access to DNA testing, many rules and regulations limit the ways in which postconviction DNA evidence can be used. In most cases, it is typical for states to require that any new evidence be brought to court within six months following a conviction in order to warrant a new trial. In the case of DNA evidence, the drawback of such a rule is obvious: It excludes individuals who were convicted before DNA typing was available but for whom such typing may now provide important evidence relevant to their cases. Since the use of DNA evidence has become commonplace, many states have revised their statutes to allow for the presentation of evidence secured through postconviction DNA analysis even after convicted persons have exhausted all their appeals.

The Innocence Project has made several suggestions for the improvement of state statutes related to postconviction DNA analysis. The organization asserts that state laws should provide for access to DNA testing wherever it can establish innocence, even in cases in which defendants have pleaded guilty; should set no absolute deadlines on when such access will expire; should provide access to currently available DNA technology, not dependent on whether such technology was available at the time of trial; should allow for flexibility in where and how DNA testing is conducted; should require the preservation of biological evidence for a reasonable period of time; and should require the disclosure of evidence that is in the custody of state officials.

In 2004, the US Congress passed the Justice for All Act; this law includes a section, known as the Innocence Protection Act of 2004, that stipulates that all convicts with reasonable claims of innocence must be granted the opportunity to prove their cases in court using postconviction DNA testing. States seeking to qualify for funding under the Justice for All Act must allow convicted persons the level of access to postconviction DNA analysis specified in the act. The Justice for All Act has been renewed several times since its introduction. As of August 2024, it was awaiting approval by the Senate.

Bibliography

Johnson, Paul, and Robin Williams. “Post-conviction DNA Testing: The United Kingdom’s First ’Exoneration’ Case?” Science and Justice 44, no. 2 (2004): 77-82.

Kobilinsky, Lawrence F., Thomas F. Liotti, and Jamel Oeser-Sweat. DNA: Forensic and Legal Applications. Hoboken, N.J.: Wiley-Interscience, 2005.

Lazer, David, ed. DNA and the Criminal Justice System: The Technology of Justice. Cambridge, Mass.: MIT Press, 2004.

Rudin, Norah, and Keith Inman. An Introduction to Forensic DNA Analysis. 2d ed. Boca Raton, Fla.: CRC Press, 2002.

Scheck, Barry, Peter Neufeld, and Jim Dwyer. Actual Innocence: Five Days to Execution, and Other Dispatches from the Wrongly Convicted. New York: Random House, 2000.

Tabachnick, Cara. "Hit in DNA Database Exonerates Man 47 Years After Wrongful Rape Conviction." CBS News, 5 Sept. 2023, www.cbsnews.com/news/leonard-mack-exonerated-47-years-after-wrongful-rape-conviction/. Accessed 18 Aug. 2024.