The challenges of identifying and classifying child sexual abuse material

Julianne Kloess, Jessica Woodhams, Helen Whittle, Timothy D Grant, Catherine Hamilton-Giachritsis

Research output: Contribution to journalArticlepeer-review


The aim of the present study was to (a) assess the reliability with which indecent images of children (IIOC) are classified as being of an indecent versus nonindecent nature, and (b) examine in detail the decision-making process engaged in by law enforcement personnel who undertake the difficult task of identifying and classifying IIOC as per the current legislative offense categories. One experienced researcher and four employees from a police force in the United Kingdom coded an extensive amount of IIOC (n = 1,212-2,233) to determine if they (a) were deemed to be of an indecent nature, and (b) depicted a child. Interrater reliability analyses revealed both considerable agreement and disagreement across coders, which were followed up with two focus groups involving the four employees. The first entailed a general discussion of the aspects that made such material more or less difficult to identify; the second focused around images where there had been either agreement (n = 20) or disagreement (n = 36) across coders that the images were of an indecent nature. Using thematic analysis, a number of factors apparent within IIOC were revealed to make the determination of youthfulness and indecency significantly more challenging for coders, with most relating to the developmental stage of the victim and the ambiguity of the context of an image. Findings are discussed in light of their implications for the identification of victims of ongoing sexual exploitation/abuse, the assessment and treatment of individuals in possession of IIOC, as well as the practice of policing and sentencing this type of offending behavior.
Original languageEnglish
Pages (from-to)173-196
Number of pages24
JournalSexual Abuse
Issue number2
Early online date1 Sept 2017
Publication statusPublished - 1 Mar 2019

Bibliographical note

This article is distributed under the terms of the Creative Commons Attribution 4.0 License ( which permits non-commercial use, reproduction and distribution of the work without further permission provided the original work is attributed as specified on the SAGE and Open Access page (

Funding: EPSRC


  • child pornography
  • child sexual abuse material
  • indecent images of children (IIOC)
  • Internet sexual offenses
  • online child sexual abuse


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