Sniffer Dogs:The Science, Investigations And Law Of Evidence

The Science:

Research indicates that the unique physiological and anatomical characteristics of canine smell enable human beings to detect drugs, explosives, and other objects with remarkable accuracy. This is because the canine olfactory system can recognize more smells than it has receptors for scent molecules and these receptors can have particular cross-reactions, forming distinct pattern systems linked to various odors. While sniffing, the air that the dog inhales is split into two different paths. The olfactory region is the destination of the upper flow channel, which accounts for 12-13% of each breath and is where odor molecules are deposited and collected. Dogs have a preference for the right nostril and what is pertinent is that, while sniffing, if the stimuli turns out to be novel, threatening, or arousing, the dog continues to use only the right nostril. The olfactory epithelium consists of, among others, olfactory receptor cells (ORCs), which are bipolar neurons extending out into the airspace to interact with odorants. From here, the olfactory nerves transfer the impulses to the olfactory bulb (OB). Here, the initial processing and filtering of olfactory information occurs. From the OB, olfactory signals are transmitted to the olfactory cortex and then to the thalamus. Here, the main olfactory epithelium (MOE) and the vomeronasal organ (VNO) play their part. VNO is not only the main structure in pheromone recognition but it can also be used in recognizing other low-volatile substances. In humans, nasal detection of volatile chemicals is mediated both by the olfactory and trigeminal systems, while in dogs, odor detection is implemented only through their olfactory neuroepithelium.

The Indian Evidence Act and Expert Evidence:

The Indian Evidence Act, 1872 under Section 45, allows the court to gather the opinion of experts upon a point of science, art, etc. when the court has to form an opinion on the same. It is no doubt that scientific developments have made a serious impact on the law of evidence and the same is commendable. But such opinions should not conclusively weigh the scales of justice. It was held in People v.Patrick that expert witnesses are affected by that pride of opinion and that kind of mental fascination with which men are affected when on scientific expeditions. Perhaps this is why expert evidence is often considered a weak type of evidence, requiring corroboration. It has been held that before acting on such evidence, it is usual to see if it is corroborated either by clear, direct evidence or by circumstantial evidence. It has also been held by the Indian Supreme Court, in Ramakant Rai v. Madan Rai, that ocular testimony was preferable to medical opinion. Additionally, when there is a variance between medical evidence and evidence of eyewitnesses, it has been

that the courts should not take the easy way of giving the benefit of doubt to the accused.

Dogs as Experts? The Settled Law:

Discovery of a fact with the help of a tracker/sniffer dog has been put in the category of scientific evidence. However, the Supreme Court has, in a cantena of cases, held that while the services of a sniffer dog may be taken for the purpose of investigation, its faculties cannot be taken as evidence for the purpose of establishing the guilt of an accused. This is for the reason that there are several inherent infirmities in the evidence based on sniffer/tracker dog. The possibility of an error on the part of the dog/master, possibility of misrepresentation, wrong inference, little scientific knowledge on the precise faculties of such dogs et cetera are a few to name. Even if the investigative authorities use such aid to reach the truth of the matter, judicial exercise cannot completely permit such endeavor. As held in AbdulRajak Murtaja Dafedar v. State of Maharashtra, there are three common objections which are raised against the acceptance of this kind of evidence. First, the dog's human companion must enter the box and record the dog's evidence, which is obviously hearsay, as it is evident that the dog cannot enter the box and deliver his testimony under oath and thus submit to cross-examination. Second, there is a belief that a person's life and freedom in criminal proceedings shouldn't be predicated on dog conclusions. Thirdly, it is suggested that such evidence should be dismissed even if it is strictly admissible under the rules of evidence since it is likely to have an excessively dramatic effect on the jury compared to its relative value.

In Dinesh Borthakur vs. State of Assam, the trial judge based the conviction of the accused on the fact that the sniffer dog had gone near the accused only and nobody else when he had been inside the house and also that the behaviour of the accused was abnormal as he had neither wept nor cried nor shown any sign of shock/grief at the scene of death of his own wife and adopted daughter. The Supreme Court while setting aside the conviction, relying on Gade Lakshmi Mangarajualias Ramesh v. State of A.P, held that the law in this behalf, therefore, is settled i.e., while the services of a sniffer dog may be taken for the purpose of investigation, its faculties cannot be taken as evidence for the purpose of establishing the guilt of an accused.

The Case in Bihar:

Despite such a settled position, the special judge (POCSO) in State of Biharv. Amar Kumar, convicted the accused under Sections 302/34, 201/34 and 376DB/34 of the Indian Penal Code and Section 4 of the POCSO Act, 2012 and sentenced him to be hanged by neck till death. In this case, a twelve-year-old girl was allegedly gang-raped, slain, and dumped on a road close to a temple, which her grandmother and herself had visited when they went to witness a fair held in honor of Nagpanchami festival. When the body was found, there were blood drops below her waist. The dead body was seized and was sent for post-mortem examination. At the spot where the body was found, a tracker/sniffing dog was brought, where it smelled the corpse before entering the home of a villager. Since nothing incriminating was discovered there, the tracking dog then entered the accused's home. At his home, the accused was taken into custody. Where the deceased person was found, four pairs of slippers, a purse, and a chain were recovered. The investigating agency assumed right at once that the accused owned one of the slippers. Moreover, even though the Trial Court had listed the evidence of the accused having closed himself inside a room, which was locked from outside, as one of the circumstances against him, there was no evidence whatsoever of the door having been broken open for arresting the accused.

The High Court of Judicature at Patna strongly disapproved of the findings of the Trial Court. It pointed out several lapses in investigation and contradictions in testimonies. Indeed, one of the witnesses to the seizure list had explicitly said that nothing was found in the accused's home after the sniffer dog had entered, and that only the accused was taken into custody. Collectively, the witnesses to the seizure stated that they had signed on a plain piece of paper. Moreover, the supposed confession of the accused was recorded before a B.D.O. but the same had no emblem of the authority of the B.D.O.

On sniffer dog evidence, the High Court also noted that there was nothing on record to get any idea about the skills of the dog used for tracking or of the handler who had trained the canine. It questioned the Trial Court's opinion on whether the sniffer dog evidence was expert evidence, even in the absence of the dog's handler having been examined in the witness-stand for his statement to qualify under Section 45 of the Indian Evidence Act, 1872. The Trial Court proceeded on the presumption that the dog would never have faulted in entering the house of the accused, while there was evidence of the dog having entered another person's house too. The High Court recognized the sharp olfactory sense of dogs which can help trace the offender but questioned its reliability and evidentiary value, especially in the absence of examination of its handler. It, therefore, held that even if the police started the investigation with a sniffer dog, that cannot be considered and received as evidence so strong as for the Trial Court not to need any corroborative evidence. It relied upon Sharad Birdhichand Sarda v.State of Maharashtra where the Supreme Court crystalized the law pertaining to circumstantial evidence and finally acquitted the accused.

While in the labyrinth of criminal justice, the steadfast contributions of sniffer/tracker dogs emerge as a beacon of reliability, sole reliance on such prowess to convict an accused is against the settled principles of criminal jurisprudence. No doubt that they are indispensable investigative tools, but we also need to underscore their training, the possibility of an error on the part of the dog/master, misrepresentation, wrong inference etc. as aforesaid. Moreover, there is little scientific knowledge on the precise faculties of such dogs. Therefore, in the interest of justice, while such evidence may only have corroborative value, it should never be the sole-basis of a conviction, much less in cases when the accused is sentenced to death.

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