This article is written by Simran Singh Rathi, a student of Army Institute of  Law, Mohali


Audiatur et altera pars is a Latin legal maxim that means “let the other side be heard as well or both the sides must be heard before passing any order”. It is based on the common law concept of natural justice which has grown leaps and bounds with the growth of civilization.   The Indian Criminal Justice system finds its roots in the British legal system which along with forming the bedrock, had passed down a multitude of common law legacies, of which, the Adversarial Legal System acts as the sheet-anchor of today’s Indian Criminal Jurisprudence but is also an amalgamation of both accusatorial and inquisitorial methods.

An Adversarial system is a system where the judgement is given by a judge after listening to the case argued upon by the prosecutor and defence. The quintessential feature being that between the parties at dispute, the judge plays a neutral role by coming to a conclusion only after ascertaining the evidence brought before him by the contesting parties and there upon decides the relevancy or admissibility of evidence. This system aims at ensuring a free and fair trial, impartiality and juridical control to provide justice to all. The neutrality of the judge provides the conflicting parties an impetus to put forth their arguments with an assurance that the concluding judgement would be based after duly listening both the parties. 

The evidence presented before the court of law plays a crucial role because the merit of the judgement depends upon the cogency of evidence; as it makes or breaks the case. As a cardinal rule in evidence law, the evidence brought before the Court to prove the facts in issue should be the best available evidence and as a settled principle of law, a Court must discharge its discretionary and obligatory functions duly in dispensing justice because it is the duty of a Court to ensure that justice prevails always.

Relevant Opinions under Evidence Act

It is an established rule that in Court, any person summoned to give his testimony as a witness to a case is strictly expected to state only the facts pertaining to the immediate case and not draw his imagination to form any opinions. But there lies an exception to this rule under the Indian Evidence Act, 1872 (hereby referred to as “Act”) where the expert witnesses, who are not Court witnesses, yet, are given a peculiar authority, where the opinions given by them on certain areas are considered relevant.   

The provisions span from Section 45 to Section 51 under Chapter – II of the Act. It was to make sure that justice is delivered without any discrepancies as a judge may not always be well-versed with the nuances and technicalities of certain spheres which are professionally complicated and sophisticated and can take resort to the opinions of persons who have gained special skills and knowledge regarding the same. Before seeking any expert opinion, it should be first established that the subject matter in the case is such that an export testimony is necessary and the expert called must possess the desired special skills.

Opinions of Experts

According to Section 45 of the Act, an expert is a person who has expertise in the fields of foreign law, science, art, the identity of handwriting or finger impressions, electronic evidence and his opinions are relevant facts. The expert aids the Judge with his skilled opinions and knowledge which are advisory in nature to reach a conclusion in the subject matter. The opinions of the expert are not to be considered as the gospel truth since they are too, witnesses themselves. But they have an upper hand as compared to other witnesses due to the exclusive knowledge they have in certain fields.

However, an expert is not a witness of fact and his evidence, in reality, is only advisory in character. An expert witness must provide the judge with the necessary criteria to test the accuracy of the conclusions and to facilitate the judge to form his independent and appropriate judgment by applying the criterion to the evidence presented in the case.

Proficiency of an Expert

The decision lies with the court to deduce the competency of credit of a witness, in this case, the expert. The test is to ensure that the witness is adequately qualified in experience. The opinions of an expert are not binding in nature for they should be and interpreted as any other evidence to the case, relevant in deciding the fact in issue. The admission or denial of opinion is upon the discretion of the court. Therefore, the opinions of the expert on any subject matter can be put through scrutiny by the adverse counsels. 

According to Section 146 of the Act, which is the weapon of cross-examination can be used by the counsel by asking questions to the expert to test his veracity over the subject matter and shake his credit so as to put forth before the Court that the particular expert can be relied upon or not. The adverse counsel can cross-examine the witness by ascertaining his qualifications and present stature in life since if the witness is not in touch with the nitty-gritty or the skills required then the court can take an inference regarding them. 

The credit of the witness can also be impeached by producing relevant evidence, in accordance with the Section 155 of the Act, where evidence against the witness in the court can either be a piece of oral evidence which can be achieved by proving him unworthy of credit through the testimony of other witnesses or by establishing that expert has been bribed to give a false deposition or prove any contradiction by the way of inconsistencies where the expert may have spoken some statement which was not divulged in the documentary report. This is usually done to in a way expose the character of the witness to ensure that the court does not lay greater emphasis on his testimony.

Further, under Section 46 of the Act, those facts are relevant if they either support or contradict the opinions of the experts which can be via numerous reports like a ballistic report, toxicology report, post-mortem report etc.

Evidentiary Value of Expert Opinion

The opinions given by an expert witness are considered to be the opinion of the third person. The opinions given by him are considered to be weak evidence for it is a mere opinion and not a fact-based testimony. The priority is given to direct or documentary evidence because under no state of affairs can it override the substantive evidence. The court has the discretionary power to decide whether the expert opinion may be accepted or denied by the court and since it is not conclusive proof the admissibility of evidence is decided by the Court. The mere assertion made without mentioning the data or basis in support of his opinion is not evidence, even if it comes from an expert. It is considered to be a grave injustice to solely base conviction only on the testimony of an expert witness without seeking any independent and reliable corroboration. since the expert is brought before the court only with a view to depose and not decide in anyone’s favour because that is a judicial duty. The judge has the disposition to reject the expert opinion even after the test of competency is fulfilled. 

Medical Evidence v. Ocular Evidence

The expert opinion by a medical official is so feeble an evidence that in case of discrepancies between medical and ocular evidence, the ocular evidence is giving prime importance and medical evidence gets discarded, the reason being that the ocular evidence is a direct testimony given by the eye witness. The common value of medical evidence is that of a weak evidence and therefore, corroborative becomes imperative. In a contradiction between the direct evidence and medical evidence, the direct evidence is given preference until the medical evidence proves to be so conclusive that it rules out the actuality of truth in the testimony given by the eye-witness.


The expert opinions are an exception to the general rule, where a witness is strictly expected to stick to the facts and the opinions and beliefs stated by him are considered to be inadmissible. But the expert witnesses are one distinct category where their opinions are relevant in the court of law. Although the court has complete autonomy so as to draw its own conclusion after due consideration of the expert witnesses and while making it admissible, corroboration is a salient feature to be ensured to uphold the sanctity of law and ideals that our Justice system stands for. 

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