Hurdles to DNA Profiling Technology
When DNA profiling technology was applied in forensic science, it was challenged in 1987 for its reliability by the defense expert of a murderer in pretrial hearing. Thus, murder trial could not be concluded on DNA testing. The controversial arguments were on methods of collection, labeling and testing of samples.
Certainly, the interpretation of the bar code pattern of a DNA profile is not easy; it needs skill and expertise. For example, a band corresponding to DNA fragment containing 10 repeat sequences many be very close to a fragment with 11 such sequences. Therefore, these two could not be distinguished. Hence, computer scanning device is needed that measures accurate size of each DNA fragment which makes bar code pattern and compares DNA profiles.
Secondly, when blood samples of criminals are collected, it may be contaminated by microorganisms, the other environmental factors like heat as it may degrade DNA. If so, there may be misleading matches or mismatches. Therefore, at every step care should be taken in carrying out the analytical work. Since the test depends on comparison of the length of different cut fragments, the DNA samples to be compared should be treated exactly in the same way as same restriction enzyme, same gel, same detective probes, etc. Inspite of precautions, some times there occurs 'band shift' which shows still carelessness. Because small differences will give .wrong result and misinterpretation. Therefore, analysis should be repeated to ensure its validity and reliability. Therefore, for forensic science accurate guidelines should be formulated and strictly followed. In this regard, the National Research Council (USA) recommended a series of safeguards for conducting DNA typing tests. In addition, the Federal Bureau of Investigation (USA) along with the National Institute of Standard & Technology have developed standards for DNA profiling (Chawla, 1998).