The positive applications of forensics and DNA

DNA Evidence

The practice of criminal justice has two goals. The first, and very important, goal, is to find and convict those who have committed crimes. The second, and equally important goal, is to make sure people are not wrongfully convicted of crimes they did not commit. The two concepts are closely intertwined, because any time the wrong person is convicted, a guilty person goes free, not facing the consequences of his or her actions, and often, also free to commit more crimes. The biological evidence of DNA helps the criminal justice system on both fronts -- both by helping to convict guilty persons and by helping to exonerate those who came under suspicion but who did not commit the crime in question.

Convicting someone of a serious crime is serious business, and the process is something that intelligent people pay attention to. Our criminal justice system is complex and many-layered, and gives every person charged with a crime many opportunities to demonstrate his or her innocence. Because of this, in the United States, a person convicted of a crime has many avenues for an appeal. Filing an appeal does not guarantee the convicted person that he or she will get a new trial, but it does mean that an impartial judge will look at the facts the convicted person has presented, and carefully consider whether that person should get a new trial or not. We see reports in the media all the time of someone who has been convicted but granted a new trial because of questions regarding things that happened in the first trial. It can also be used to prevent the abuse of the appeals process. As an example, in a New Jersey case, on appeals the DNA evidence was found to be valid. The DNA evidence contributed significantly to a man being convicted of stabbing someone to death. In the commission of the crime he had cut himself or been cut, and his DNA was left behind at the crime scene (Zolper, 1996).

Trials, of course, depend on evidence and challenges to evidence. The prosecution puts forth their evidence that the person committed the crime, and the defense puts forth evidence of the person's lack of guilt. One of the most powerful pieces of evidence the prosecution can put forward today is DNA evidence. "DNA" stands for Deoxyribonucleic acid, found in the nucleus of each cell in the body. DNA testing is genetic testing. Since, with the exception of identical twins, it is highly unlikely that two individuals would have exactly the same DNA patterns, when DNA is present at a crime scene it can sometimes contribute significantly to the identity of the perpetrator. One classic example of the use of DNA is in cases of rape, where the rapist may leave behind DNA from several sources including saliva and semen.

However, in the same way that DNA can help identify the perpetrator of a crime, it can also help eliminate people who have fallen under suspicion. In the example above of rape, it may be that an ex-boyfriend of the victim might be suspected of the crime. By taking a DNA sample from that suspect and by comparing it to DNA evidence gathered from the victim, this person can easily be ruled in or out as the perpetrator. This is crucial to the process of criminal investigation. As suspects are ruled out those facts guide the investigators to work more vigorously in other directions.

However, DNA can also serve justice after conviction has occurred. The Law School at Northwestern University has run a program for some years now serving selected people who believe they were convicted wrongly. By the year 2002, they had proven that 18 prisoners on Illinois' "Death Row" had been wrongfully convicted (Zwerdling, 1998). In Virginia, Earl Washington was freed from Virginia's "death row" after ten years when DNA testing proved that he was not the person who had raped and killed a victim (Barry, 2005).

Under the United States system of justice, we are obligated to find and convict those who commit serious crimes to the very best of our ability. At the same time, as a country with the death penalty, it is crucial that we convict those who are truly guilty of the crime committed, especially in death sentence cases. When DNA can conclusively demonstrate that the accused committed the crime, the country's citizens can have confidence that justice has prevailed. When we use DNA to go back and re-evaluate old cases and free someone who was wrongfully accused, justice has prevailed again. In addition those cases can then be reopened so the real perpetrator will be caught and brought to justice.