Forensic science may be defined as a science applied to matters of law. Forensic science is science used for the purpose of the law and thus any branch of science used in the resolution of legal disputes is forensic science. In the broadest sense, forensic science is any science used in the resolution of legal conflicts.

The word forensic is rooted in Latin word forensis. The dictionary meaning of word the forensic is relating to court or law or relating to court of law. But in legal terminology it may mean the science which deals with the principles and practice of different branches of science which elucidates doubtful questions in court of justice. It is a science composing of those matters which may be considered as common ground to both the scientists and the legal practitioners.

The ancient Roman forum was the site of debate concerning governmental issues, but it also was the courthouse, where trials were held. Therefore, forensic science has come to mean the study and practice of applying natural and physical sciences to the just resolution of social and legal issues. Its use by the legal system distinguishes it from other science; the expectation of routine appearances in a court of law distinguishes a forensic scientist from other scientists.

Forensic science subsists coming together with law and science. Even though forensic science has been identified intimately with the criminal justice system in the past, now the forensic scientist plays a gradually more active role in civil proceedings and in regulatory issues.

Virtually no limitation exists to the scope of physical evidence that is gist for all forensic scientists. Physical evidence may range in size from the microscopic (for example, a pollen grain) to the macroscopic (for example, a diesel truck). This wide meaning covers criminal prosecutions in the widest sense, together with patrons and ecological safeguard and physical condition and protection at work, as well as civil proceeding such as violate of agreement and negligence.

Forensic Science is basically the application of science to law. Forensic science is used to investigate criminal cases involving a victim, such as assault, robbery, kidnapping; rape, murder and civil cases such as forgeries, fraud, or negligence. Forensic science also determines as to whether laws or policies have been dishonored in the marketing of items relating to food and drink, manufacturing of medicine, agricultural particular use, automobile discharge observance, consumption water cleanliness, and monitoring international secret nuclear weapons etc.

Principles Of Forensic Science

The principles of forensic science guide the disciplines and methodologies of science in analysing the evidence to answer certain questions. These principles of forensic science have an impact upon criminal proceedings which start from the point of investigation upon the occurrence of a crime till the conviction of the accused in the court of law. The principles of forensic science which are significant in criminal proceedings are as follows:

1. Locards Principle: Sir Adman Locardo, a pioneer in criminology and forensic science, gave the basic principle of forensic science every contact leaves a trace. This principle holds that the perpetrator of a crime will bring something into the crime scene and leave with something from it. This principle is associated with the trace evidence collection at the crime scene.
    
2. Law of individuality: Every individual, natural or manmade, has a distinct quality or characteristic which is not duplicated in any other form. The most distinctive character associated with law of individuality is fingerprints which has a judgemental role in forensic science.
    
3. Law of exchange: Law of exchange states that when a criminal or his instrument comes in contact with the victim or the objects surrounding him he leaves some trace behind so that these traces are helpful for investigation purposes.
    
4. Law of progressive change: It states that everything changes with the passage of time and its impact on criminal investigation is immense because the crime scene and the criminal undergo changes and sometimes become unrecognizable.
    
5. Law of comparison: This principle compares only the people with similar likes whereas people having dissimilar likes are not compared.
    
6. Law of analysis: It means collection of the correct samples and their preservation for better analysis. The evidences have to be preserved in the prescribed manner to avoid tampering and destruction.
    
7. Law of probability: All the identifications and identities are sometimes consciously and unconsciously correct based on circumstances.
    
8. Law of circumstantial facts: Facts never lie but men can lie. Facts cannot be wrong, it cannot lie, it cannot be wholly absent. Therefore the importance of circumstantial facts is good for oral evidence.

Thus Forensic Science is that scientific discipline which is directed to the recognition, identification, individualization and evaluation of physical evidence by the application of the principles and methods of natural sciences for the purposes of administration of criminal justice.