Before I venture to elaborate on the role played by experts in shaping the opinion of the Courts, it is imperative first and foremost to understand who really an expert is. In layman's language, an expert can be inferred as:
Someone ( a person ) who has special knowledge, skill or experience in any particular field like foreign law, science, art, handwriting or finger impression etc by virtue of having acquired it through years of unremitting focus, learning, practice, observation and proper studies which others don't have and which is what distinguishes them from the rest.

This alone explains why the opinion of experts is so sought after and is valued immensely in shaping the opinion of not only people but also of the Courts and very rightly so !

Section 45 of the Indian Evidence Act also discloses who all can be called experts. It says that, When the court has to form an opinion upon a point of foreign law or of science or art, or as to identity of handwriting 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 persons are called experts. Section 45 itself proves beyond a straw of doubt that the court in all such cases when it has to pronounce judgment in a case where the opinion upon a point of foreign law or of science or art, or as to identity of handwriting or finger impressions is required, it prefers to take the opinion of those persons who are specially skilled in it by virtue of which they are called experts and such opinion certainly constitute relevant facts. Also, here it must be borne in mind that the opinion of such experts which constitute relevant facts play a major role in shaping the opinion of the court and in arriving at a reasonable and right decision.

As per the Stroud's Judicial Dictionary, Expert witness is one who has made the subject upon which he picks a matter of particular studies, practicing or observation and he must have a particular and special knowledge of the subject.

According to Black's Law Dictionary, an expert is defined as:
A person who, through education or experience, has developed skill or knowledge in a particular subject, so that he or she may render their opinion that will assist the fact hindered. Sukumar Ray in his book 'Outlines of Indian Evidence Act' on page 156 writes that, An expert witness is one who has made the subject upon which he speaks a matter of particular study, practice or observation ; and he must have a special knowledge of the subject. It is also pointed out by Sukumar pertaining to the object of expert opinion that, The purpose of expert opinion is two fold. Firstly, to obtain opinion as to the matter of skill or science which is in controversy and Secondly, to exclude the opinion as to the effect of the evidence in establishing controverted facts.

Phipson narrates the role and duty of an expert in his own words in his book on 'Evidence' in 14th edition on page 829. He writes that, An expert is not a witness of fact. His evidence is of an advisory character. The duty of an expert witness is to furnish the judge with the necessary scientific criteria for testing the accuracy of the conclusion so as to enable the judge to form his independent judgement by the application of the criteria to the facts proved by the evidence. No sane person will ever dare to disagree with what Phipson has said. The sole job of an expert is to furnish the judge with the opinion on any matter with the necessary scientific criteria and logical reasoning by virtue of which a judge can after taking into account the opinion so furnished arrive at a rational and independent decision without getting biased in any manner!

Lawson defines expert in his book on 'Expert Testimony' in 2nd edition on page 229 as : An expert is a person who has special knowledge and skill in a particular calling to which the inquiry relates.

The basic parameter of deciding the competency of an expert as put by Lord Rusell in US Shipping Board v Ship St Albans, 1931 PC 189 is this:
Is he peritus ? Is he skilled ? Has he adequate knowledge ? Let me tell my readers here that 'peritus virtute official' means the holder of some official position which requires and, therefore, presumes a knowledge of that law.

Cross in his book on 'Evidence' on page 322 writes that:
The courts have been accustomed to act on the opinion of experts from early time. Thus, the value of experts in enabling the court to determine the right conclusion in any given case especially where the case hinges on the expertise opinion cannot be overstated.

In Bal Krishna Das Agrawal v Radha Devi, AIR 1989 SC 1966, an 'expert' was defined as a person who by his training and experience has acquired the ability to express an opinion but an ordinary witness does not possess this quality.

In Ramesh Chandra Agrawal v Regency Hospital Ltd (2009) 9 SCC 709, it was held by the Supreme Court that:
The law of evidence is designed to ensure that the court considers only that evidence which will enable it to reach a reliable conclusion. The first and foremost requirement for an expert evidence to be admissible is that it is necessary to hear the expert evidence. The test is that matter is outside the knowledge and experience of the lay person.

Thus, there is a need to hear an expert opinion where there is a medical issue to be settled. The scientific question involved is assumed to be not within the court's knowledge. Thus cases where the science involved, is highly specialised and perhaps even esoteric, the central role of an expert cannot be disputed. The other requirements for the admissibility of expert evidence are:

1. that the expert must be within a recognised field of expertise;
2. that the evidence must be based on reliable principles, and
3.  that the expert must be qualified in that discipline.

It was also held in this very case that, The opinion of an expert may not have any binding effect on the court. The court does not become functus officio because of an expert opinion. It is not the province of the expert to act as judge or jury.

It is not always that the expert evidence is imperative. There have been many such instances where the expert evidence has been dispensed with as it was felt that the evidence of an ordinary witness is sufficient. As for instance, in Rajinder Bajaj v Indian Tanning Industries, AIR 2008 Delhi 62 (D.B.), where glaring discrepancies were visible even to the naked eye in the admitted signature and disputed signature, the Delhi High Court said that the reference to a handwriting expert in such a case was not necessary.

Also, there are many such cases where the courts have held that absence of an expert report is not fatal to the prosecution case. As for instance, in Vineet Kumar Chauhan v State of UP, AIR 2008 SC 780, the Supreme Court has held that where fire-arms are used in a crime, the absence of the report of a ballistic report is not always fatal to the prosecution case.

Let me clarify here that experts evidence in no manner helps the court in interpretation of the law and is only an opinion evidence and it is entirely within the discretion of the court whether to accept it or not. In fact, in Forest Range Officer v P Mohammed Ali, AIR 1994 SC 120, it was held by the Supreme Court that, Expert opinion is only opinion evidence and is not helpful to the Court in interpretation of the law.

Let me point out here that in another case – Fakhruddin v State of MP, AIR 1967 SC 1326, it was held by the Apex Court that:
Both under this Section and Section 47 the evidence is of an opinion, in the former by a scientific comparison and in the latter on the basis of familiarity resulting from frequent observations and experience. In either case, the Court must satisfy itself by such means as are open that the opinion may be acted upon.

It thus becomes clear that the courts must not believe unflinchingly in experts evidence and before accepting it must satisfy itself completely about whether it is worth to be acted upon or not. The guiding principle for courts who have to deal with experts opinion have been aptly summed up by Supreme Court in Dayal Singh v State of Uttaranchal, AIR 2012 SC 3046 wherein it held that:
The expert is not only to provide reasons to support his opinion but the result should be directly demonstrable. The court is not to surrender its own judgment to that of the expert or delegate its authority to a third party, but should assess his evidence like any other evidence. The purpose of expert testimony is to provide the court with useful, relevant information.

The purpose of an expert opinion is primarily to assist the court in arriving at a final conclusion. Such report is not binding upon the court. The court is expected to analyse the report, read it in conjunction with the other evidence on record and then form its final opinion as to whether such report is worthy of reliance or not.

In Kanchan Singh v State of Gujarat, AIR 1979 SC 1011, it was held that credibility and competence of an expert are material questions. Where the High Court did not believe an expert the Supreme Court did not interfere.

Let me reveal here that the expert evidence which is rendered as opinion of the third person is admissible under Sections 45 to 51 of the Evidence Act. Under these provisions a third person even though he/she is unknown to the facts of a particular case is called upon by the court wherever and whenever it feels imperative to seek such opinion on a particular point on which the expert by virtue of expertise on that point is best suited to give an independent, unbiased and logical opinion by virtue of which the court can also rely on it and give a sound and logical judgment based on it. It is however solely the discretion of the court on whether to accept the opinion rendered by expert or reject it and the opinion rendered by expert is not binding on it.

Let me also reveal here that the expert opinion is a very weak type of evidence and is advisory in character. Courts refrain from passing an order of conviction solely on the basis of expert evidence because they are not conclusive and may be biased in favour of the party who calls him. As for instance, it was held in Gulzar Ali v State of Himachal Pradesh, (1998) 2 SCC 192 that:
It must be borne in mind that an expert witness, however impartial, he may wish to be, is likely to be unconsciously prejudiced in favour of the side which calls him. Moreover, let us not be oblivious of the palpable fact that a witness who is remunerated always has an unconscious bias in favour of the party who called him even though he may not be tutored.

Also, it cannot be lost on us why Wellman had very candidly remarked that:
Expert witness become so warped in their judgement by regarding the subject in one point of view, that, even when conscientiously disposed, they are incapable of expressing candid opinion.

Charles Hollander in his book on Documentary Evidence in 8th edition in para 21-23 has quoted the observation of Cresswell in the Ikarian Reefer's Case (1993) 2 Lloyd's Rep 68(81) to highlight what all precautions an expert witness should take so that it remains unblemished and appears reliable for courts to fall back upon while pronouncing judgment and these are as follows:

1. Expert evidence presented to the Court should be, and should be seen to be, the independent product of the expert uninfluenced as to the form or content by the exigencies of litigation
2. An expert witness should provide independent assistance to the court by way of objective unbiased opinion in relation to matters within his expertise.
3. An expert witness should state the facts or assumption upon which his opinion is based. He should not omit to consider material facts which could detract from his concluded opinion.
4. An expert witness should make it clear when a particular question or issue falls outside his expertise.
5. If an expert's opinion is not properly researched because he considered that insufficient data is available, then this must be stated with an indication that the opinion is no more than a provisional one. In cases where an expert witness who has prepared a report could not assert that the report contained the truth, the whole truth and nothing but the truth without some qualification, that qualification should be stated in the report.
6. If after exchange of reports, an expert witness changes his view on a material matter having read the other side's expert's report or for any other reason, such change of view should be communicated ( through legal representatives ) to the other side without delay and when appropriate to the court.
7. Where expert evidence refers to photographs, plans, calculations, analyses, measurements, survey reports or other similar documents, these must be provided to the opposite party at the same time as the exchange of reports....

Let me tell my readers that while it is true that in many cases the courts have refrained from convicting a person solely on the basis of expert evidence or opinion but what cannot be denied is that it has also accepted expert opinion many times. As for instance, in Murrarilal v State of MP, AIR 1980 SC 531, it was held by Apex Court that the opinion of finger print expert is of higher value in comparison to the opinion of handwriting expert because science of identification of finger print is so perfect and therefore the rise of an incorrect opinion is practically nonest.

In Jaspal Singh v State of Punjab, AIR 1979 SC 1708, it was held by the Supreme Court that the science of identifying thumb impression is an exact science and does not admit of any mistake or doubt. So, the opinion of an expert regarding identification of thumb impression is relevant within the meaning of Section 45 of the Indian Evidence Act.

Also, in Kanbikarsar Yadab v State of Gujarat, AIR 1966 SC 821, it was held by the Supreme Court that opinion of hair expert is admissible in evidence because by the microscopic examination of the hair it is possible to say whether they are the same or of different colours or sizes and from the examination it may help in deciding where the hairs come from.

We must also bear in mind that there have been many such cases where when there is any inconsistency and the direct evidence is not satisfactory, the evidence has been corroborated by that of expert in a particular field. As for instance, in Gurucharan Singh v State of Punjab, AIR 1963 SC 340, it was held by the Supreme Court that where the direct evidence is not satisfactory or disinterested or where the injuries are alleged to have been caused with a gun and they prima facie appear to have been inflicted by a rifle, undoubtedly the apparent inconsistency can be cured or oral evidence can be corroborated by the evidence of a ballistic expert.

Also, there have been many cases where opinion of expert have been relied upon when corroborated by circumstantial or other evidence. As for instance, in Lall Chand v State of Punjab, 2010 CrLJ 699, it was held by the Supreme Court that opinion of a handwriting expert can be relied upon when due corroboration of such opinion through ocular and circumstantial evidence is provided.

In yet another case – Shashi Kumar v Subodh Kumar, AIR 1964 SC 529, it was held by Apex Court that:
Expert opinion is opinion evidence and it cannot take the place of substantive evidence. It is a rule of procedure that expert evidence must be corroborated either by clear direct evidence or by circumstantial evidence.

All said and done, it can be said with considerable certainty that the role of experts in shaping the opinion of the courts cannot be undermined even though they cannot be always relied on unflinchingly and this is more true in case of handwriting experts which I have discussed above in considerable detail. But at the same time we have also seen that on many occasions the courts have not refrained from basing their conviction on expert evidence as in the case of fingerprint expert. So it all varies from case to case but no court will ever take the risk of completely undermining the evidence of expert and whatever opinion is given by them in front of court is always taken with full seriousness and very rightly so !

Sanjeev Sirohi, Advocate
s/o Col BPS Sirohi, A 82, Defence Enclave,
Sardhana Road, Kankerkhera, Meerut-250001, UP