DNA: Reevaluating Innocence and Guilt
DNA: Reevaluating Innocence and Guilt
“DNA testing has an unparalleled ability both to exonerate the wrongly convicted and to identify the guilty.” - Chief Justice John Roberts Jr. Human beings share many qualities. Billions of people have brown eyes, millions have blonde hair; some people are short and some are tall. However, one thing that is completely unique to an individual is DNA. No two people, including identical twins, have the exact same DNA (Bruder et al., 2008). This information is invaluable to forensic scientists; since 1986 when DNA was introduced as a forensic method, DNA profiling has been used to prove guilt or innocence (Friedman, 1999). Unfortunately for many, the lack of sufficient DNA testing has led to inaccurate guilty charges. Over the years, DNA testing has become an essential element in criminal cases. As it has become more important, many cases have been reopened and untested DNA has been analyzed. This has not only led to the rightful conviction of thousands of criminals, but also the exoneration of many innocent people given guilty sentences.
In 1985, geneticist Alec Jeffreys first described DNA fingerprinting. He was the first to discover DNA regions that contained repeating DNA sequences; he also discovered that the number of times a sequence repeated itself differed from person to person. Dr. Jeffreys then created a way to measure the length of these repeated sequences, in turn creating the first way to perform human identity tests (Butler, 2005). That same year, Dr. Jeffreys was contacted about genetically proving maternity so that mother Christiana Sarbah could keep her son Andrew with her in England. They both provided blood samples with which Dr. Jeffreys produced their DNA fingerprints. After recreating the father’s DNA from Christiana’s three known children, Dr. Jeffreys matched half of Andrew’s DNA bands with his father and the other half with Christiana. The probability of this happening by chance was one in a trillion; Christiana’s son was allowed to remain in England (DNA Fingerprinting, 2003).
In 1987, the first use of DNA in United States courts appeared. Charged with armed burglary and rape, Tommie Lee Andrews was convicted after semen collected at the crime scene matched his blood sample (Hibbert, 1999). In 1989 Gary Dotson became the first person in the United States to be exonerated through the use of DNA identification technology. Convicted for rape in 1979, Dotson spent ten years in jail and on parole before his charges were dismissed (Gross, 2004). As a result of a FBI software pilot project in 1990, The Combined DNA Index System (CODIS) was created. Over the years, both computer and DNA technology have improved, thus enabling CODIS to improve alongside them. Presently, CODIS is used for the search and storage of short tandem repeat (STR) profiles (The CODIS Software). A New York case in 1991 highlighted the importance of preserving evidence when Charles Dabbs, convicted of rape in the early 1980s, was exonerated after DNA testing of a semen sample proved his innocence (Foderaro, 1991).
The second generation of DNA analysis, known as the polymerase chain reaction (PCR), became applicable to forensic analysis in 1993-94. This allows DNA to be collected from very small amounts of biological material. Then in 1995, the OJ Simpson trial brought DNA evidence into the public’s eye. The third generation of DNA analysis was developed in 1996; named short tandem repeats (STR), this allowed DNA to be extracted from even smaller amounts of material (Moffeit et al., 2007). Obviously, over the last two and a half decades DNA testing and its importance in criminal cases have steadily increased. Though DNA is vital in bringing the guilty to justice, it has also played a significant role in exonerating hundreds of innocent people sentenced to jail and/or even death. With the help of the Innocence...
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