DNA Evidence and its admissibility
For last 2 decades the DNA has become a good instrument of investigation to find the truth. The DNA examination is part of ‘Forensic Science’. The term ‘Forensic Science’ includes of all sciences as well as jurisprudence. It is science through which material evidence is collected preserved and analysed to be produced in a court of law. Finding answer to the involvement of accused in the offence, Forensic science takes help from chemistry, Medicine, Surgery, Photography, Physics, Mathematics, Biology (including Molecular Biology and Generic engineering etc.). this science includes Anthropology, Hair and Fibers Studies, Finerprings, Odontology, Entomology, Pathology, Toxicology, Forensics of questioned documents and hand writing. DNA profiling and matching is still in its development stage.
Human body consists of about 60 trillion cells and each cell has essentially a nucleus. In the nucleus of each cell there are choromosomes which store coded information in the form of sequences of different chemicals and these sequences determine out physical, mental and other characteristics. Each human nucleus contains about 5 picograms of DNA.
In the present era DNA matching and identification evidence has become new father in the cap of investigating and prosecuting agencies. In criminal as well as in Civil cases the DNA techniques are used through out the world. DNA profiling is being used in the cases of rape, murder, kidnapping, illegal abortion, abandonment of child, inheritance, immigration, assassination, infanticides and exchange of babies. Few popular cases which used DNA profiling ar Rajiv Gandhi, N.D. Tiwari, Premananda Swami Case and famous Tandoor case of Delhi. Internationally also sone of the renowned cases are Clinton-Lawinsky Case, O.J. Simpson case etc.
The acceptance of DNA profile evidence has also raised considerable controversies and concerns even in the countries where is has emerged and originated. The Evidence Act provides for consideration of the opinions of experts and at times their opinions are accepted also. Mapping, Matching, comparing, corelating, confirming and contrasting between two samples is the requirement of law. Forensic expert may be produced before the court to testify their report. When these expert evidence is produced before the court, the duty is casted upon the court to find out if these piece of evidences are corroborated with the evidences produced by the prosecution or the defence.
The Apex Court in number of cases have reached out to the pros and cons of these evidences and at times these expert evidences have been discarded. The Apex Court has held in catena of judgments held that the credibility of otherwise credible visual evidences, if contradicts or they are inconsistent with ocular evidence. It is also necessary to note down that the Apex Court in one of the case has held that no person can be compelled to give his blood or any tissue as sample for DNA testing and matching. Later in one another case the Apex Court held that proof coming out from DNA cannot be said to be self incriminatory because it is already present in the body. The Supreme Court in this case held that if a person has committed a crime, he would never voluntarily give samples of blood since he fully knows that he has committed crime and the legal system never be purpose of the law to protect a convict.
1. Leela Ram v. State of Gujarat AIR 1999 SC 717
2. Gautam Kundu v. State of W.B. AIR 1993 SC 2295
3. Sharda v. Dharampal AIR 2003 SC 3450