Expert Witness Advocacy Training at the Inner Temple London

I recently had the incredible opportunity to participate in a mock trial at the Inner Temple in London (see previous blog about the training). This wasn’t just any mock trial; it was a specialised training session for British barristers focused on the authentication of open-source intelligence (OSINT) and the emerging C2PA standard.

The goal was to see how these new forms of digital evidence would be practically interrogated by practitioners. After having worked with the TRUE Project and the Institute for International Legal and Advocacy Training (IILAT) on designing elements of the training material, I was invited to get in the witness box myself and provide expert witness testimony.

The case

Our fictional case centered on a war crime in Yemen, where a fighter pilot was accused of a “double-tap” airstrike. For the purposes of the workshop, the prosecution’s case was built on OSINT – though in a real-life setting, there would be more evidence of other kinds, e.g. witness testimony, however.

For the first time in a setting like this, we introduced C2PA metadata as supporting evidence. This metadata came from a C2PA-compatible camera (a Sony Alpha 7 IV). Secondly, there was a second set of attestations: what seemed to be verifications from an investigative journalism collective, added to the same video which we found on TikTok. My role was to present and defend the prosecution’s expert report, which detailed how the evidence was collected and verified.

What the video in question might have looked like in the Content Credentials Verifier tool

It was fascinating to see how skilled barristers, with little to no background in digital forensics, approached this new-to-them type of evidence. They were sharp, methodical, and their line of questioning really put the technology to the test. The experience underscored a few key things for me.

First, the absolute necessity of intellectual honesty for an expert witness. Your primary duty is to the court, to present the facts as clearly and truthfully as possible, regardless of who hired you. Second, the importance of clear communication. I found myself relying on analogies to explain complex technical concepts, avoiding jargon wherever possible. It’s a challenge to bridge the gap between the worlds of technology and law, but it’s a crucial one to overcome.

While the training was a success, I did feel we got a bit bogged down in some of the more basic technical details, like the removal of C2PA data from a file. This prevented us from diving deeper into some of the more nuanced and complex aspects of C2PA verification that I was hoping to explore. For future trainings, I think a more interactive and collaborative format would be beneficial. It would allow us to work together to establish best practices for presenting and interrogating this kind of evidence.

Or perhaps, the onus is on me to write a different expert report, which would assist the examination in really getting to the nitty-gritty, and to the actual claims we might derive from provenance metadata!

This experience was a powerful reminder that as technology continues to evolve, so too must our legal frameworks and practices. The C2PA standard has the potential to bring a new level of transparency and trust to digital evidence, but it also presents new challenges. It’s only through cross-disciplinary collaboration between technologists and legal professionals that we can ensure these new tools are used responsibly and effectively in the pursuit of justice.

I’m incredibly grateful to have been a part of this training and to the many individuals and organisations that made it possible. It was another step forward in my journey to becoming an expert witness and a valuable learning experience that I will carry with me.