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The strength and fidelity of the U.S. criminal justice system, like any other in the world, results from and depends on an ability to convict a wrongdoer and exonerate an innocent. Unfortunately, sometimes the pitfalls of the system and its methods lead to opposite results. As stated in Furman (2003), “The wrongful conviction of an innocent person is the worst nightmare to anyone who cares about justice” (p. 11). Another tragedy of the system is that, for decades, the public has been concerned primarily with the inability of the justice system to punish the guilty ones. However, the tragedy deepened when the realization came that punishing the wrong person for something he/she had not done was by far worse. This new perspective has resulted in the following equation, “For every innocent person wrongfully convicted, a guilty person roams free” (Furman, 2003, p. 11). Conviction can appear wrongful under two basic conditions. The first one suggests that the convicted person is de facto innocent. The second one presupposes the presence of procedural errors that have violated the person’s rights. The DNA evidence has become a powerful and ultimately precise tool in determining wrongful convictions, and in emphasizing their very existence as well as magnitude, in the first place. The post-conviction DNA testing not only locates wrongful convictions, but also helps to make the rightful ones. Thus, when the wrongful blame is shifted off one person, it may be at the same time put on the one who did commit a crime (Roman, Walsh, Lachman, & Yahner, 2012; Furman, 2003; “Postconviction testing,” 2012).


Before the era of a DNA analysis and its availability in the field of forensics, the convictions were based on other types of evidence. Many of them contributed greatly to deviating justice from its course. In fact, wrongful convictions have always been a part of the whole picture. The research on wrongful convictions dates back to the beginning of the twentieth century. In 1913, Edwin Borchard’s article opened the eyes of Americans on the issue. In the 1930s, his book with an eloquent title Convicting the Innocent: Sixty-Five Actual Errors of Criminal Justice caused quite a resonance. It described the actual 65 cases when innocents were wrongfully convicted. The book named the main reasons for it, i.e. some sources of errors, such as faulty circumstantial evidence, false confessions, erroneous eyewitness testimony, and prosecutorial excesses (Gould, 2010). Unfortunately, many, if not all, of these reasons have remained and persisted through the whole century of the criminal justice history. Numerous recent studies conclude that the faulty forensic evidence and false eyewitness testimony are still the primary causes for wrongful convictions. The studies present particularly disturbing and dissatisfactory results. The research pertaining Illinois, made public in January 2003, reported that at least 13 of the 167 inmates on a death row in Illinois (i.e. approximately 8%) were innocent.

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According to Gould (2010), during the 1990s, when the DNA testing became widely available and feasible, it exonerated 250 innocent persons, including a few defendants sentenced to death. A 1987-year study of potentially capital cases found as many as 350 cases of wrongful convictions in the U.S.A. between 1900 and 1984. Even the most conservative estimates, where 99.5% of convictions are thought to be valid, have showed that 7,700 innocent people were wrongfully convicted of serious crimes in the year 2000, alone. Thus, if the one focuses on the percentage, the system of justice may seem almost flawless and perfectly functioning. However, if the person concentrates on the number of people, this perception changes, and the amount of human tragedy becomes vivid beyond the pure numbers and statistics. The most recent Garrett’s (2008) study has showed that false eyewitness testimony contributed to a wrongful conviction in 79% of examined cases; and the faulty forensic evidence was observed in 55% of wrongful convictions. Inter alia, such evidence as hair comparison or bite mark has been associated with a low degree of reliability because they often provided some links to a wrong person. Confessions are one more category of ambiguous evidence. False confessions, including confessions under pressure, also contribute to a general number of wrongful convictions. The predecessor of DNA evidence, i.e. the blood type evidence, can also result in wrongful convictions if the two suspects have the same blood type. In general, the estimated rate of wrongful convictions in the twenty-first-century America reaches as much as 3 to 5% (Roman et al., 2012; Furman, 2003; Gould & Leo, 2010).

The DNA evidence has revolutionized the system of justice and added a considerable amount of precision to it. Unlike simple blood tests and hair analysis of the previous years, DNA tests work on a molecular level. It is the evidence on the stage of the genetic code. The genetic material is present in nearly all cells of the body, which makes it relatively easy for a person to leave and for forensics to collect and analyze. A DNA sequence is a code unique for every individual which means the possibility of errors is minimized and close to zero. However, forensic specialists do not analyze the whole sequence. Instead, they create DNA profiles from the available forensic evidence and compare them to a profile of a known person or profiles from other crime scene evidence. The DNA profile is a series of numbers, each one representing the number of repeated DNA patterns at a particular location on the DNA molecule (Roman et al., 2012).

A pioneer of the DNA analysis in the field of criminal justice is Alec Jeffreys who suggested, theorized, and advocated the use of DNA as evidence and an investigation tool in the 1980s. The first DNA-based criminal investigation took place in 1986 in England. It was based on Jeffreys’ technique known as the restriction fragment length polymorphism (RFLP). Despite the revolutionary nature and effectiveness, the technique had several drawbacks, such as slowness and large amounts of intact DNA required. The 1990s brought a technical advancement that allowed Jeffreys’ revolutionary approach to find a new form of realization, namely polymerase chain reaction (PCR) analysis. The latter one analyzed short tandem repeats (STR) in DNA and produced multiple copies. As long as technological progress gained momentum, newer methods of testing appeared and enabled forensics to perform the DNA testing of degraded, aged, partial, or otherwise compromised biological evidence to get less inconclusive results. Up until nowadays, the PCR method, accompanied by some new technological opportunities and an enhanced procedure of analyses, is favored as a primary method of DNA identification. PCR/STR operates the noncoding parts of the genome, thus, does not reveal any physical or biological traits of a person. It serves as merely an identifier for matching a sample with a person. The match means that the evidence sample belongs and links the crime to the suspect. Nonmatching samples mean that the suspect is clean, i.e. not involved in the crime or a crime scene, in particular. When associations are found, law enforcement agencies use them to aid the investigation and prosecution. Respectively, DNA testing can be done post factum for earlier convicted persons. Sometimes, second investigation that includes DNA testing into the evidence base proves convictions to be wrongful (Roman et al., 2012; “Postconviction testing,” 2012).

A survey of more than 300 crime laboratories in the U.S.A. conducted in 1983 reveals that 75% of labs have analyzed blood, semen, hair, and other forensic evidence and 90% conducted drug examinations. The similar survey dated back to 2002 shows a dramatic transformation of crime laboratories and a shift in their focus. By 2002, 351 publically funded crime labs had opened and operated in the United States. About 61,000 requests pertained the DNA analysis (Roman et al., 2012). Prior to that, in 1996, the National Institute of Justice released a report which said that in, “every year since 1989, in about 25% of the sexual assault cases… the primary suspect has been excluded by DNA testing” (Gould & Leo, 2010).

There exist different models for post-conviction DNA testing. A traditional model presupposes that a wrongfully convicted person openly claims his or her innocence, or other people do it on his/her behalf. Then, governmental agencies or advocacy groups react to this claim. The DNA analysis is done near a final stage of a post-conviction relief review. The aforementioned means that all relief actions, such as investigations and DNA testing, in particular, start after the petition is made. In other words, the detection of wrongful convictions occurs because people make claims about their innocence and request the DNA analysis. The drawback of this scheme is that innocent people who do not make claims remain undetected. There also exists a Virginia (VA) model of post-conviction DNA testing. Unlike the traditional model, the DNA analysis occurs at the beginning of the scheme. Thus, the decision to conduct DNA testing does not result from the convicted person. Instead, the state is funded to test all available physical evidence that might contain DNA for serious crimes. The Virginia state experience is unique, however, it has proved to be efficient and viable (Roman et al., 2012).

Everything started with a law that was passed in 2001 in Virginia and gave convicted persons a right for testing the newly discovered as well as added, or old, but previously untested DNA materials. Under the governor’s initiative, the new legislation piece and the funding of the National Institute of Justice (NIJ), all 534,000+ existing cases from 1973 to 1987 have been collected and brought to the Central Lab for a revision. There were a few parameters that narrowed the list down in several stages. The first parameter presupposed the presence of the retained physical evidence narrowing the list down to 3,000 cases. The second parameter demanded the presence of a known suspect, which deducted the number of cases to 2,100. Another mandatory requirement was the felony conviction which brought the remaining list down to roughly 740 cases. Felony specification for homicide, sexual assault, or non-negligent manslaughter cut the list down to 634 cases. Depending on a crime type, the study showed a 5 to 15% of wrongful convictions (Roman et al., 2012; “Research on DNA’s role,” 2012).


In conclusion, DNA testing is a new, highly effective, although still not absolutely flawless or a 100% precise tool in preventing an error of wrongful convictions and exonerating the already convicted innocents. Unfortunately, the power of DNA analysis is limited to some cases with the DNA evidence. It is reported that fewer than 20% of violent crimes have the biological evidence to retrieve DNA. In the majority of past cases, it was not properly collected and/or appears unavailable for a further testing. Nevertheless, the DNA evidence has been a major breakthrough in fighting errors in the justice system. DNA testing has done even more. It has helped detect and unveil the frailties of previously used forensic methods and allowed for their reassessment for the sake of further perfecting the system (Gould & Leo, 2010).

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