forensic science

FORENSIC SCIENCE

The term forensic is derived from the Latin word “forensis” pertaining to a forum and belonging to courts of justice or to public discussion and debate.

Forensic science consists of all the branches of science and  their applications in the  justice system.  Originally, all the techniques were borrowed from various discipline like chemistry, medicine, surgery, biology, photography, and mathematics.

PRINCIPLES OF FORENSIC SCIENCE

There are seven forensic science principles:

forensic science
  • Principle  of individuality
  • Principle of exchange
  • Principle  of progressive change
  • Principle of comparison
  • Principle  of analysis
  • Principle  of probability
  • Principle  of circumstantial facts

PRINCIPLE OF INDIVIDUALITY

Every object natural or man – made are individual in character, that cannot be duplicated . It is unique.

The law of individuality is fundamental in forensic science. Anything that is involved in the crime scene is unique. Thus the culprit is unique, his weapon of offence is unique, scene of crime isunique, evidentiary clues, leftover and picked up by the culprit are unique. We only have to identify the uniqueness to link the crime with the criminal

   PRINCIPLE OF EXCHANGE

 The French scientist Edmond locard formulated the basic principle “Whenever two identities comes in contact, mutual exchange of traces take place”. The law of exchange is also known as locard’s principle of exchange.

When a criminal or his weapon of crime comes in contact with the victim or the objects surrounding him, thus the mutual exchange of traces takes place between the criminal, victim and the object involved in the crime.

Thus the Edmond locard considered as the ‘father of modern forensic science’.

PRINCIPLE OF PROGESSIVE CHANGE

Everything changes with the passage of time.

Nothing is permanent immutable. The rate of change varies with different objects and under different situations.

The scene of occurrence undergoes rapid changes. The objects of the crime scene, the weather, the human beings, undergoes changes in comparatively short period of time.

PRINCIPLE OF COMPARISON

Only the likes can be compared with the likes.

It is the principle of comparison. It emphasis that the necessity of providing corresponding samples/specimens for comparison with the questioned samples/specimens.

PRINCIPLE OF ANALYSIS

Anything can be analysed.

The principle analyzed the necessity of correct sampling and correct techniques for useful and worthwhile results.

PRINCIPLE OF PROBABILITY

Anything can be identified with the help  of probability.

Probability is a concept: it determines the chances of occurrence of a particular events in a particular way, out of a number of ways in which the events take place or fail to take place with equal facility.

Ps=Ns/Ns+Nf

Where, Ps represents the probability, Ns no. of ways in which the event can successfully take place, and Nf no of ways in which it fails.

PRINCIPLE OF CIRCUMSTANTIAL FACTS

Facts do not lie, Men/Women can and do.

It indicates the importance of circumstantial facts than the evidence of eyewitness. The testimony of the eyewitness is modified by auto suggestion, external influence, opinions of others, conscious or unconscious bias and rationalization.

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