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Forensic Computing: Prohibited Images of Children

January 05 2023

The Legislation

In the late 1970s it was recognised that it was necessary to create legislation in order to counteract the sexual exploitation of children caused by the taking and distribution of indecent images of those children. This legislation was included in the Protection of Children Act 1978 which remains, with amendments, in force today. Also addressed within this act was the making of indecent pseudo-photographs. An example of a pseudo-photograph would be the superimposition of the face of a child onto the body of an adult within a pornographic image.

At that time, pornographic drawn images of children were not included within the legislation. These were potentially covered within the remit of the Obscene Publications Act but that was before the Internet, World Wide Web, and before Computer Generated Images (CGI) became commonplace.

In the first decade of the current century, such drawn and CGI images started to surface in quantity, on the Internet. Some of those images were (and remain) disturbing in the extreme and could be said to demonstrate the breadth of human imagination. The legislation at that time was inadequate to address this material. The images were deemed not to comprise pseudo-photographs and were therefore not contrary to the Protection of Children Act 1978, and the Obscene Publications Act concentrated on the publication, rather than the possession, of such images.

In order to address the issue of highly sexualised, but non-photographic, images of children the offence of the possession of a prohibited image of a child was created by Section 62 of the Coroners and Justice Act 2009. Such an image must:

  • Be pornographic
  • Focus solely or principally on a child's genitals or anal region, or depict one of a number of specific sexual acts specified at subsection 7 of the Act
  • Be grossly offensive, disgusting or otherwise of an obscene character

A pornographic image must reasonably be assumed to have been produced (rather than possessed) solely or principally for the purpose of sexual arousal.

All the criteria above have to be fulfilled so there is a relatively high bar to be crossed in relation to this offence. That bar is readily crossed by the type of images referred to earlier, but not always, in our experience, in some of the images that we see charged.

The legislation defines a child as being a person under the age of 18 years. If the subject of the image is drawn with clearly pre-pubescent or pubescent characteristics, then the assessment of age is unlikely to problematical. However, the assessment of photographs of apparently post-pubescent children is already well known to be challenging. As such, the assessment of drawn images of post-pubescent children can dramatically increase that challenge.

Assessment Issues

Two particular issues are commonly encountered:

“Can the image be reasonably assumed to have been produced solely or principally for the purpose of sexual arousal?”

Some images are clearly, to an objective observer, produced for that purpose and that purpose alone. Frequently, however, we are presented with images of characters such as “Bart and Lisa Simpson” or those from the “Family Guy” cartoon series engaged in sexual activity. Whilst such images may be considered to be in poor taste, there is a strong argument to be made that their intended purpose is that of adolescent humour rather than sexual gratification.

“Is the image of a child?”

Perhaps the most frequent issue encountered as to whether the image is a child is in relation to some “Hentai” images that are charged as prohibited images of children.

“Hentai” is a form of erotic cartoon “art” originating in Japan. It was traditional, in less enlightened times, for western cartoon artists to depict characters of East Asian ethnicity with very narrow slanted eyes. Conversely, within Hentai, characters are generally drawn with huge round eyes which, to a western observer, may give them a child-like appearance. Such characters are often charged as prohibited images of children despite being drawn with greatly enhanced secondary sexual characteristics (notably very large breasts and narrow waists), not to mention squirrel ears and bunny tails.

Section 65 of the Coroners and Justice Act 2009 does include a proviso that the subject is to be treated as a child if “the predominant impression conveyed is that the person shown is a child despite the fact that some of the physical characteristics shown are not those of a child”. A holistic view of the image and its apparent origin must therefore be taken.

Technical Issues

Technical issues (both in the digital and legal senses) include whether the images are accessible to a user, whether a user can be shown likely to have been aware of their presence, or whether, if they have been downloaded, the user deleted them shortly after the download.

It should be noted that the offence is one of possession and for such an offence to complete, the accused must have had custody and control of the images on the date(s) charged. This is of particular relevance in relation to forensically recovered images for which no provenance can be established. The mere presence of such unprovenanced images does not mean the user had custody and control.  This is something that has to be assessed in each case.


Section 64 (1) of the Coroners and Justice Act 2009 outlines several defences:

  • that the person had a legitimate reason for being in possession of the image concerned;

This would most likely relate to persons engaged in the analysis of devices relating to the prosecution or defence of alleged offences under this act.

  • that the person had not seen the image concerned and did not know, nor had any cause to suspect, it to be a prohibited image of a child;

This could include the automatic downloading of an image from an adult pornography web page to a browser cache. It should be noted that the entire content of a web page may be downloaded, not only that part visible to a user.

(c) that the person—

(i) was sent the image concerned without any prior request having been made by or on behalf of the person, and

(ii) did not keep it for an unreasonable time.

An example could comprise an unrequested image received via social media or email. This could also be applicable in relation to cached images from a website not dedicated to such material.

Evidence Review

Section 62 of the Coroners and Justice Act 2009 defines clear criteria which must ALL be fulfilled for an image to be considered a prohibited image of a child. At Keith Borer Consultants, a Digital Forensic Consultant will initially focus on two main areas of investigation. The order in which these areas are addressed may be influenced by the nature of our instructions.

Technical issues

Is there any evidence that the user would have been aware of the allegedly unlawful images? At this point, the origin of the image, the presence or absence of relevant search behaviour and any record of the accessing of the images will be considered. We would consider things like whether the images were user accessible, and whether they were viewed but immediately deleted without being copied.

The images

KBC can assist by reviewing the charged images and drawing to the Court’s attention any images which may not clearly fulfil the criteria, for example the subject’s age. All aspects of the nature, and potentially the context, of the images will be considered and objectively reported upon. It is, of course, ultimately for the Court to decide whether such an image fulfils the necessary criteria. In our experience, we often find images falling short of the necessary criteria required to prove the offence, or that “knowing possession” cannot be demonstrated.

Please email kbc@keithborer.co.uk or call 0191 3324999 if you would like to discuss your case.


Steve Guest

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