A Kiss is Just a Kiss: Lip Print Identification in the Criminal Law Bulletin

A periodical for lawyers, the Criminal Law Bulletin, recently published an article on “The Investigative and Evidential Uses of Cheiloscopy (Lip Prints).” [1] The author argues that “concerns about the reliability of lip prints evidence are unfounded” and “that lip prints evidence is admissible evidence.” The legal analysis rests on misconceptions about American and English law, but I won’t spell these out. Instead, I want to comment on the author’s approach to the validation of a technique for scientific identification.

According to the article, the following facts apparently demonstrate that “[c]heiloscopy has a scientific foundation”:

• “Human lips are made up of wrinkles and grooves, just like fingerprints and footprints. Grooves are of several types and these groove types and wrinkles form the lip pattern which is believed to be unique to every individual.”
• A 1970 article in the Journal of the Indian Dental Association reported that “none of the lip prints from the 280 Japanese individuals showed the same pattern.”
• In a 2000 article in the same journal, “Vahanwala and Parekh studied the lip prints of 100 Indians (50 males and 50 females) and concluded that lip prints are unique to individuals” and that “It can therefore be conclusively said — Yes, lip prints are characteristic of an individual and behold a potential to be recognized as a mark of identification like the fingerprint!”
• "Saraswathi et al. studied 100 individuals, made up of 50 males and 50 females, aged 18 - 30, and found that ‘no individual had single type of lip print in all the four compartments and no two or more individuals had similar type of lip print pattern.’"
• “A study by Sharma et al [published, as was the previous study, in the Taiwanese Journal of Dental Sciences] also found that lip prints are unique to every individual.”
• Tsuchisashi studied 1364 Japanese individuals, 757 males and 607 females, aged 3 - 60 years and found no identical lip prints. . . . [T]he lips of the twins frequently showed patterns extremely similar to those of their parents [but nonetheless distinguishable].”

These studies do not address the relevant questions. The hypothesis that lip prints are unique is neither a necessary nor a sufficient condition for forensic utility. Before a method of identification can be considered valid, research should establish that multiple impressions from the same person are typically closer to one another than two impressions from different individuals [2] and that they so much closer that an examiner can accurately classify pairs according to their source. Until these questions are asked and answered, the caution expressed in an article not mentioned in the Criminal Law Bulletin seems apt: “Although lip print identification has been utilized in the court of law in isolated cases, more research needs to be conducted in this field . . . .” [3]

References

1. Norbert Ebisike, The Investigative and Evidential Uses of Cheiloscopy (Lip Prints), 47 Crim. Law Bull. No. 4, Art. 4 (Summer 2011)

2. David H. Kaye, Questioning a Courtroom Proof of the Uniqueness of Fingerprints, 71 Int’l Stat. Rev. 521 (2003), available at http://ssrn.com/abstract=944365

2. Shilpa Patel, Ish Paul, Madhu Sudan Astekar, Gayathri Ramesh, Sowmya G V, A Study of Lip Prints in Relation to Gender, Family and Blood Group, 1 J. Oral & Maxillofacial Pathology No. 1 (2010), abstract available at http://journalgateway.com/index.php/ijomp/article/view/V.1.I.1.Art1