27/07/2026
VVVVI. MUST READ JUDGEMENT.
جناب جسٹس سید شہباز علی رضوی کا ڈی این اے ٹیسٹ کے بارے انتہائی معلوماتی فیصلہ۔
ڈی این اے ٹیسٹ کی مختلف تکنیک اور اصلاحات کے بارے میں مکمل معلومات
When a biological sample is collected in a sexual assault investigation, it may contain a mixture of s***m cells (if present) and non-s***m cells.
The sample undergoes differential extraction, a laboratory procedure that separates the sample into two fractions:
1) S***m fraction
2) Epithelial (non-s***m) fraction.
DNA is then extracted separately from each fraction for comparison with reference samples. Epithelial fraction refers to the extraction of the non-s***m cells, which can be:-
(I) The “victim” vaginal, cervical, oral mucosal epithelial cells along with some white blood cells.
(II) The “offenders” skin, buccal epithelial cells, white blood cells and immature s***m cells.
Because the non-s***m fraction in vaginal swabs is ordinarily dominated by the victim’s epithelial cells, John M. Butler notes that it is commonly referred to as the female fraction in sexual assault evidence.
The s***m fraction is the fraction enriched for s***m cells following differential extraction.
DNA obtained from this fraction is analysed to determine the source of the s***m cells recovered from the evidence.
Presence of an offender’s DNA in the epithelial fraction is supportive evidence indicating that the offender’s non-s***m cells were also present in the sample. However, by itself, DNA detected in the epithelial fraction cannot establish that sexual in*******se, ej*******on, or pe*******on occurred. Conversely, recovery of the offender’s DNA from the s***m fraction is consistent with the offender being the source of the s***m cells recovered from the sample. The objective of differential extraction is to separate s***m cells from non-s***m cells. Consequently, when the laboratory procedure is successful, the offender’s DNA may be recovered only from the s***m fraction, while the epithelial fraction may predominantly contain the victim’s DNA. According to the United States National Institute of Justice (NIJ) and John M. Butler’s Advanced Topics in Forensic DNA Typing Methodology, there is no forensic principle requiring an offender’s DNA to be present in both the s***m fraction and the epithelial (non-s***m) fraction. A DNA profile obtained from the s***m fraction alone may constitute strong forensic evidence, provided that validated laboratory methods were followed, quality assurance standards were met, and the results are interpreted in the context of the entire body of evidence. Hence, absence of the offender’s DNA from the epithelial fraction does not, by itself, invalidate or diminish the credibility and probative value of the matching DNA profile obtained from the s***m fraction.
Crl. Appeal.31263/22
Manazir Ali Vs The State etc
Mr Justice Syed Shahbaz Ali Rizvi
ADVOCATE CHAUDHARY ZUBAIR
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