Cheiloscopy in Criminal Justice: Evaluating Population-Based Uniqueness and Legal Challenges in India

Cheiloscopy is the study of the characteristic patterns on the lip created by the sulci labiorum, or wrinkles and grooves on the labial mucosa. Lip prints have been identified as available supplementary tool in forensic science, given their distinct patterns and wide range of applicability, similar to fingerprints. It can be crucial in positively identifying an individual’s identity, a person’s presence or absence at the crime scene. They are specific to each individual, with the exception of monozygotic twins, and they remain unalterable even after death. This discipline, together with fingerprint analysis and dental record comparison, forms a cornerstone of scientific forensic identification methods.

A comprehensive literature review was conducted using a targeted search strategy in the PubMed/Medline database, focusing on full-text articles containing the keywords “lip,” “lip print,” and “Human identification.” Relevant data were extracted, categorized under several headings like journal, country of authors, study, aims, outcomes, tool, sample, etc. This information was analyzed, with further examination of cited references.

The most widely accepted classification for lip prints is the Suzuki and Tsuchihashi Classification, which provides a clear and comprehensive description of common lip patterns. Lip prints found on diverse surfaces-such as binding tape, glasses, cigarette butts, or windows-can serve as vital evidence in numerous crimes. These can be registered using various methods such as direct photography, usage of lipstick or using substances like aluminum powder or lysochrome dyes. Accurate transfer and recording of lip prints using suitable media is crucial for their validity as reliable forensic evidence.

The stability and individuality of lip prints, unaffected by age and shared genetic factors, render them a valuable biometric marker, complementing fingerprints for personal identification.