Role Of Expert Witnesses In Criminal Cases
Expert witnesses play a crucial role in criminal trials, where their specialized knowledge can provide critical insights into complex aspects of a case. These witnesses are typically professionals or individuals with specific expertise in areas such as forensic science, medicine, psychology, ballistics, toxicology, DNA analysis, and more. Their role is to assist the court in understanding technical or scientific evidence that may not be within the general understanding of the judge or jury.
In criminal cases, the testimony of an expert witness can be a determining factor in establishing guilt or innocence, especially in cases involving forensic evidence or technical elements. However, the court always scrutinizes the credibility and relevance of the expert’s testimony to ensure it contributes to a fair and just outcome.
Legal Framework for Expert Witnesses in Criminal Cases
In Pakistan, expert testimony is governed under the Qanun-e-Shahadat Order, 1984 (Law of Evidence). According to this law:
Section 45 of the Qanun-e-Shahadat permits experts to provide opinions on matters that require specialized knowledge.
Section 47 permits a court to rely on the opinion of an expert if the subject matter is related to the scientific, technical, or specialized knowledge of the expert.
1. The Role of Expert Witnesses
Expert witnesses are called upon to:
Explain complex scientific principles and technical findings in ways that are understandable to the judge or jury.
Provide opinion evidence on matters requiring specialized knowledge, for example, DNA evidence, ballistics analysis, or mental health evaluations.
Testify on causality or probability in relation to injuries, deaths, or other key aspects of the case.
Help assess the reliability of evidence, particularly in cases involving forensic or medical reports.
2. Types of Expert Witnesses in Criminal Cases
Forensic Experts: Involved in DNA analysis, toxicology, autopsy reports, and evidence processing.
Psychiatric Experts: Called in cases involving the mental state of the accused, including evaluations of insanity defense.
Ballistics Experts: Testify on the trajectory and behavior of bullets, firearms identification, and analysis of shooting incidents.
Medical Experts: Involved in cases requiring analysis of injuries, cause of death, or medical conditions of the victim or accused.
Document Experts: Analyze handwriting, signatures, or any other questioned documents, such as in cases of fraud or forgery.
3. Case Law Analysis: Expert Witness Testimonies
Below are several landmark cases where expert witness testimonies played a pivotal role in criminal proceedings.
4. State v. Aftab Ahmed (2004, Pakistan)
Case Overview:
In State v. Aftab Ahmed, the accused was charged with murder under Section 302 of the Pakistan Penal Code (PPC). The primary evidence in the case was forensic—a DNA analysis that linked the accused to the victim.
Legal Issue:
The issue was whether the DNA evidence presented by an expert witness could be deemed admissible and reliable in proving the identity of the accused as the perpetrator.
Court’s Decision:
The court admitted the DNA analysis as valid evidence, as it was conducted by a certified forensic expert. The expert testified that the blood samples from the scene of the crime matched the DNA profile of the accused, providing strong evidence of his involvement in the crime.
Outcome:
The accused was convicted of murder, largely due to the strong scientific testimony provided by the forensic expert.
Legal Principle:
The case highlighted the critical role of forensic experts, particularly in cases involving DNA evidence, to establish the identity of the accused and support the criminal charge.
5. Faisal Khan v. The State (2012, Lahore HC)
Case Overview:
In Faisal Khan v. The State, the accused was charged with rape. The main evidence was medical testimony provided by a forensic medical expert, who conducted a physical examination and gave an opinion on the victim’s injuries and whether the evidence supported the claim of sexual assault.
Legal Issue:
The key issue was whether the forensic testimony was sufficient to establish that the victim had indeed been sexually assaulted, and whether the absence of direct physical evidence could be compensated by expert testimony.
Court’s Decision:
The Lahore High Court ruled that the testimony of the forensic expert was admissible and credible. The expert testified that the injuries on the victim were consistent with rape and that the victim's medical examination corroborated her version of events.
Outcome:
The accused was convicted based on the expert's testimony, although the court emphasized that corroborating evidence should always be sought in serious offenses like rape.
Legal Principle:
This case underscored the importance of forensic testimony in cases involving sexual assault where direct evidence may be difficult to obtain, and the expert's opinion can play a significant role in substantiating the victim's allegations.
6. Zeeshan v. The State (2015, Islamabad HC)
Case Overview:
In Zeeshan v. The State, the accused was charged with murder following the shooting death of a victim. A ballistics expert was called to testify on whether the gun used in the incident was capable of firing the fatal shots and whether the bullet recovered from the victim matched the weapon in question.
Legal Issue:
The central issue was whether the ballistics expert's testimony could link the accused's weapon to the fatal injuries sustained by the victim.
Court’s Decision:
The Islamabad High Court accepted the ballistics expert's opinion, which confirmed that the weapon used was consistent with the wounds found on the victim and could have caused the fatal injuries. The expert also explained how the trajectory of the bullet corresponded to the positioning of the victim and the scene of the crime.
Outcome:
The expert testimony led to the conviction of the accused. The Court emphasized the weight of scientific evidence, particularly in ballistics and forensic analysis.
Legal Principle:
The case reinforced the crucial role of expert witnesses in cases involving weapon identification, ballistics analysis, and fatal injury causation.
7. Shahbaz v. The State (2018, Sindh HC)
Case Overview:
In Shahbaz v. The State, the accused was charged with drug trafficking under the Narcotics Control Act, 1997. The toxicology expert was called to explain the chemical composition of the drugs seized from the accused and whether they were illicit substances as defined by the law.
Legal Issue:
The issue was whether the expert's testimony regarding the chemical analysis of the substances seized from the accused could establish intent to traffic drugs, which is a key element in criminal drug cases.
Court’s Decision:
The court ruled that the toxicology expert's testimony was admissible and persuasive. The expert provided detailed analysis showing that the substances seized were illegal narcotics, and that their quantity and purity were consistent with drug trafficking activities.
Outcome:
The accused was convicted of drug trafficking based on the expert's scientific analysis of the substances, along with other circumstantial evidence.
Legal Principle:
The case reinforced that chemical analysis and toxicology expert testimony are indispensable in drug-related offenses, where the nature and quantity of substances play a vital role in proving criminal intent.
8. Khalid v. The State (2020, Peshawar HC)
Case Overview:
In Khalid v. The State, the accused was charged with fraud after allegedly forging bank documents to embezzle funds. An expert witness in document examination testified that the signatures on the documents were forged and did not match the original signatures on record.
Legal Issue:
The issue was whether the expert's testimony regarding the authenticity of the documents could be sufficient to establish criminal intent and fraud.
Court’s Decision:
The court found the testimony of the document expert to be reliable, and the expert’s detailed analysis helped establish that the documents in question were fraudulent.
Outcome:
The accused was convicted of fraud and forgery based on the expert's testimony.
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