Dna DNA evidence is extremely helpful in criminal trials not only because it can determine the guilt of a suspect, but also because it can keep innocent people from going to jail. The suspect must leave a sample of their DNA at the crime scene in order for testing to occur, but DNA can be found in the form of many things such as semen, blood, hair, saliva, or skin scrapings. According to Newsweek, “thousands of people have been convicted by DNA’s nearly miraculous ability to search out suspects across space and time .. hundreds of innocent people have also been freed, often after years behind bars, sometimes just short of the death chamber” (Adler ). Though some may think it is a waste of time to go back and attempt to release convicts from prison after they have been in jail for such a long time, but since DNA testing had proven to be quite a successful method of doing this, it could help in many ways. First of all, if a person is not guilty of a crime they are in prison for committing, they have every right to attempt to prove their innocence. A great advantage to releasing these innocent people from prison is that they allow for more room in prisons for those who are actually guilty of the crimes. Another reason people may object to DNA testing in the courtroom is that the tests require the suspect to provide a sample of his own DNA.
The only problem with this is that sometimes, suspects refuse to donate their DNA for testing. In a situation in St. Petersburg, FL, a man was being followed because he allegedly matched the description of a man who was suspected of committing fifteen robberies and two rapes. As the police followed him on his motorcycle, he stopped at a red light and spat on the ground. As soon as the police saw this, they got out of the car and collected the saliva with a paper towel.
The DNA from the saliva was a perfect match with the DNA from the semen collected from the rape victims. Puetz, the investigator on the case defends the constitutionality of his evidence-gathering methods; the courts, he says, have held that once you’ve put out your trash, you’ve waived your right to keep the contents private, and “I don’t see why the same wont hold true for saliva.”(Adler). Because there are many different types of crimes, it is often difficult to find enough physical evidence to convict a person. For example, in rape cases there is usually only a small amount of physical evidence, so cases are based on word alone. Because of DNA testing we can now take samples from the victim and attempt to match the results with those of the suspect. Therefore, DNA is sometimes the only real way of determining the guilt or innocence of a suspect without having any witnesses. Since many rape cases are left unsolved, DNA testing is believed to be the most accurate way of keeping sex offenders off the street.
Because of the growing trend of using DNA in rape cases especially, a company in Brooklyn now advertises a small flashlight-like device intended to be used to jab at attackers in order to collect a sample of his skin for later use (Adler). According to a study by Joseph Peterson, with the Department of Criminal Justice at the University of Illinois, DNA evidence does not have a major impact on the decision to either convict or acquit defendants, but weighs heavily on sentencing, and often leads to more severe penalties (Peterson, Banbury Report). Some may think that DNA testing in rape cases, especially in the case of incest, is not totally valid because the samples of semen, or other bodily fluids may be contaminated with the DNA of the victim, which would produce different results. In cases of incest, DNA could be so alike because of heredity that the results may be hard to distinguish between the victim and rapist. Though many people believe this to be true, in all actuality “each person’s DNA typing pattern is different and virtually unique.”(Genetic DNA Typing). As well as placing a suspect at a crime scene, DNA tests can also be performed if there is no suspect.
DNA from the crime scene is collected, and the results are run through a series of indexes known as the CODIS system. This system contains the DNA profiles from other convicted criminals and sex offenders for the specific reason of finding matches in cases where no suspect is found. “By the summer of 1999, the 99 labs using CODIS had made 218 forensic hits. Thus, CODIS matched one or more forensic profiles to an offender sample .. As a result of these CODIS hits, the participating laboratories aided 578 investigations.” (Loftus).
The main reason DNA evidence should be admissible in courtrooms because it is the most accurate form of evidence. Samples may only be admitted into court as evidence after they go through a series of steps to make sure the evidence is relevant to the case and will help the jury or judge reach a verdict. The judge must decide if the test is accurate by the Frye rule, and can withhold the results if he thinks the test will confuse the jury. The Frye rule is “the law’s traditional yardstick for determining admissibility of scientific evidence, (with) directed attention to the general acceptance of a technique within its particular scientific field” (Shultz, Billings). In order to introduce DNA evidence into a case, the judge analyzes the privacy that may be invaded by testing. The five factors which are analyzed in order to introduce genetic evidence are “1) the seriousness of the need, 2) the intrusiveness of the technique, (3) alternative methods that are less intrusive, (4) reliability of the instrument, and (5) capacity for limitation and control” (Westin, Banbury Report). The most important reason DNA testing should be used in criminal courts is that is the most accurate form of evidence available.
Because DNA testing is simply another form of fingerprinting that is more detailed, there is currently no other method of identification that is as technologically advanced, with as small a rate of inaccuracy. Though there is a small chance of producing false evidence, with the ever-changing techniques, genetic specialists are able to test more sections of DNA at a time, which will produce a better “picture” of the DNA strands. In the future it may get so detailed that we will be able to recognize actual features and ethnicity from DNA combinations; this is why the term “DNA fingerprinting” is not the most accurate way to describe the technique. It doe not lead to the identity of a person unless there is a sample with which to compare it. Scientists are in the process, however, of developing databases where every person will have a sample placed. Until then, however, statistics are used in order to estimate the number of people who could possibly carry the combination of DNA strands that match a sample given for testing “Like everything else in the scientific world, nothing about DNA (profiling) is %100 assured”(Problems with DNA Fingerprinting).
Errors are very rare, and preventable because the statistics used to calculate the probability are said to be the most accurate way at this time to determine the actual number of matches that could be possible. In order for the DNA test to be admissible in court, the probability of a match must be very low to keep from accidentally placing a person at the crime scene when he or she was actually not. All the scientists are trying to do is to improve the chances of a match. Using more probes and testing more sites are helping keep the mismatches out of the lab. For example, if eight sites are tested rather than the usual six, the probability of a match will go up.
In order for the jury to grasp the concept of testing, the statistics must be high enough for them to interpret. Appropriately, 1 in 1,000,000,000 would be more powerful than 1 in 10,000,000. . Because the jury is not as knowledgeable to the subject of DNA testing, it is necessary that when presenting evidence, that the numbers used in court are ratios using numbers that the typical person could understand and comprehend. Though it is hard to determine how powerful DNA testing could be in the future, it is obvious that it is the most accurate and conclusive form of evidence available at this time.
Some believe though, that DNA tests take away the defendants rights to a speedy trial. In some cases, where testing may take months because of its complexity, this is true. But in most cases testing can be performed in a matter of weeks or even days depending on the number of tests to be performed. In any case, the future should be prepared for the ever-changing technology of DNA testing and welcome it warmly. It is helpful and has helped in many cases that would have otherwise gone unsolved.
As John Adler stated in a Newsweek report, “DNA typing is a tool with vast potential, but only if it is used wisely, with an awareness of human nature—the kind you don’t need an electron microscope to see” (Adler). Science Essays.