1) Introduction :

                  The general rule is that opinion of a witness on a question, whether of fact or law is irrelevant. Opinion of expert (third person) is relevant under section 45 as an exception to this general rule. These are the parties not directly or indirectly connected in any manner to the suit or proceeding which is pending in the court, but they are called by the Court to assist the Court, when the Court cannot form the judgement himself. Section 45 to 51 of Indian Evidence Act 1872 lays down the provisions relating to "opinion of experts/ third person when relevant. Section 45 deals with facts bearing upon opinions of experts, Section 47 deals with opinion as to handwriting when relevant. Section 47A provides for opinion as to digital signature , when relevant. (It is inserted by IT Act 2000) Section 48 deals with opinion as to existence of right or custom when relevant. Section 49 deals with opinions as to usages , tenets etc., when relevant Section 50 deals with opinion on relationship, when relevant.  and Section 50 provides for grounds of opinion, when relevant.

2) Who is Expert ? 

        An expert is a skillful professional in a particular field capable of possessing specialized knowledge concerning the matter in issue, which a common man cannot possess.
3) Definition of opinion of Experts : 

      Section 45 of Indian Evidence Act defines Opinions of experts as, "When the Court has to form an opinion upon a point of foreign law, or of science, or art, or as to identity of hand writing or finger-impressions, the opinions upon that point of persons specially skilled in such foreign law, science or art, or in questions as to identity of handwriting or finger impressions, are relevant facts. Such person called experts.


(a) The question is, whether the death of A was caused by poison. The opinions of experts as to the symptoms produced by the poison by which A is supposed to have died, are relevant.

(b) The question is whether A, at the time of doing a certain act, was by reason of unsoundness of mind, in capable of knowing the nature of the act, or that he was doing what was either wrong or contrary to law. The opinions of experts upon the question whether the symptoms exhibited by A commonly show unsoundness of mind, and whether such unsoundness of mind usually renders persons incapable of knowing the nature of the acts which they do, or knowing that what they do is either wrong or contrary to law, are relevant.

(c) The question is, whether a certain document was written by A. Another document is produced which is proved or admitted to have been written by A. The opinion of experts on the question whether the two documents were written by the same person or by different persons are relevant.

             The expert witnesses are the persons who have not seen a commission of a particular act  and they are not personally  interested in the suit or proceeding but they are called upon to help the Court pf law. According to  Section 45 of the Indian Evidence Act, the Court refers to the opinions of the persons specially skilled in foreign law, Science, Art or as to the Identity of handwriting or finger impressions, and the opinions are relevant and admissible. Thus the opinion of expert witness plays an important role in the matter of evidence and enables the Court to arrive at proper conclusion. The experts opinion is only a piece of evidence and cannot be taken as substantive piece of evidence since it is to be judged along with other evidence. 

Mohd. Zaid v. State of Tamil Nadu 1999 Cr LJ 3699

      In this case Supreme Court held that the Evidence of a doctor conducting post mortem without proceeding any authority in support of his opinion is not sufficient to grant conviction to an accused.
4) Relevancy of Opinion :

i) Opinion of examiner of Electronic Evidence (Section 45A)

         When in a proceeding, the court has to form an opinion on any matter relating to any information transmitted or stored in any computer resource or any other electronic or digital form, the opinion of the Examiner of Electronic Evidence referred to in section 79A of the Information Technology Act, 2000 (21 of 2000), is a relevant fact.

 Explanation - For the purposes of this section, an Examiner of Electronic Evidence shall be an expert.

ii) Facts bearing upon opinions of experts (Section 46) :

           Facts, not otherwise relevant, are relevant if they support or are inconsistent with the opinion of experts when such opinions are relevant.

Illustrations : 

          (a) The question is, whether A was poisoned by a certain poison.  The fact that other persons who were poisoned by that poison, exhibited certain symptoms which experts affirm or deny to be the symptoms of that poison, is relevant.

          (b) The question is, whether an obstruction to a harbour is caused by a certain seawall. The fact that other harbours similarly situated in other respects, but where there were no such sea-walls, began to be obstructed at about the same time is relevant.

iii) Opinions as to handwriting, when relevant (Section 47)

                 When the Court has to form an opinion as to the person by whom document was written or signed, the opinion of any person acquainted with the handwriting of the person by whom it is supposed to be written or signed that it was or was not written or signed by that person, is a relevant fact.

Explanation –
            A person is said to be acquainted with the handwriting of another person when he has seen that person write, or when he has received document purporting to be written by that person in answer to documents written by himself to under his authority and addressed to that person, or when in the ordinary course of business document purporting to be written by that person have been habitually submitted to him.

Illustrations :

             The question is whether a given letter is in the handwriting of A, a merchant in London. B is a merchant in Calcutta, who has written letters addressed to A and received letters purporting to be written by him. G is B’s clerk, whose duty it was to examine and file B’s correspondence. D is B’s broker, to whom B habitually submitted thee letters purporting to be written by A for the purpose advising with him thereon.

           The opinions of B,C and D on the question, whether the letter is in the handwriting of A, are relevant though neither B, C or D ever saw A, write.

iv) Opinion as to digital signature when relevant (Section 47A)

        When the Court has to form an opinion as to the "digital signature" of any person, the opinion of the Certifying Authority which has issued the Digital Signature Certificate is a relevant fact.

v) Opinion as to existence of right or custom when relevant (Section 48)

           When the Court has to form an opinion as to existence of any general custom or right, the opinions as to the existence of such custom or rights, of persons who would be likely to know of its existence if it existed, are relevant.

Explanation –

         The expression “general custom or right” includes customs or right common The Orient Tavern any considerable class of persons.


The right of the villagers of a particular village to use the water of a particular well is a general right within the meaning of this section.

vi) Opinion as to usage’s, tenants, etc., when relevant (Section 49)

        When the Court has to form an opinion as to - the usage’s and tenants of any body of men or family, the constitution and government of any religious or charitable foundation, or the meaning of words or terms used in particular districts or by particular classes of people, the opinions of persons having special means of knowledge thereon, are relevant facts.

 vii) Opinion on relationship, when relevant (Section 50) 

         When the Court has to form an opinion as to the relationship of one person to another, the opinion, expressed by conduct, as to the existence of such relationship, or any person who, as a member of the family or otherwise, has special means of knowledge on the subject, is a relevant fact:
        Provided that such opinion shall not be sufficient to prove a marriage in proceedings under the Indian Divorce Act, 1869 (4 of 1869) or in prosecutions under section 494, 495, 497 or 498 of the Indian Penal Code (45 of 1860).


         (a) The question is, whether A and B were married. The fact that they were usually received and treated by their friends as husband and wife, is relevant.

         (b) The question is, whether A was the legitimate son of B. The fact that A was always treated as such by members of the family, is relevant.

viii) Grounds of opinion when relevant (Section 51) : 

        Whenever the opinion of any living person is relevant, the grounds on which such opinion is based are also relevant. Illustration An expert may give an account of experiments performed by him for the purpose of forming his opinion.

5) Evidentiary Value of Expert Opinion/ Admissibility of Expert  :

                      According to Section 45 of Indian Evidence Act, 1872 before a person characterized as an expert, it is necessary that there must be some material on record to show that he is skilled in particular science and is possessed of a particular knowledge concerning the same. He must have special study of the subject or acquired special experience therein. Thus testimony of witness becomes admissible, his competency of an expert must be shown, may be, by showing that he was possessed of necessary qualification or that he has acquired special skilled therein by experience, It is for judge his expertisation of the particular subject.

6) Case Law : 

a) In S. Gopala Reddy v. State of A.P ,  it was held that the evidence of an Expert is a weak type of evidence and court consider it is unsafe to relay on it without independent and reliable corroboration.

b) In Anwar Vs.State of Haryana, 1997) SCC 766, it was held by the Court If the medical evidenceis totally inconsistent with the occular evidence it would be permissible for the court to reject the oral evidence thougghbmedical evidence is opinion evidence.



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