All the Evidential Eggs in One Digital Basket
As Chico Marx said in Duck Soup, “Well, who ya gonna believe me or your own eyes?” Humans put great store in their visual abilities (which makes sense, given its predominance in our sensory systems) and we tend to believe what we see. That’s why magic tricks work: They distract our attention and lead us to accept what we’ve seen as real. As Teller, the quiet half of Penn and Teller, has said, “Magicians have done controlled testing in human perception for thousands of years.” But what happens when that perception isn’t for entertainment but to catch a criminal? If a picture is worth a thousand words (or not), surely a video of thousands of pictures must tell us more, yes?
Police are increasingly relying on closed circuit television (CCTV) footage to observe the public, review alleged criminal activities, identify suspects and charge them, and eliminate persons of interest, among other uses. Some of the footage (an anachronism) is from public spaces, such as highway or parking lot cameras. The public may be captured on government CCTV, by cameras in stores, or by residential cameras (like home security systems or smart doorbells), as well as on public transport, car cameras, and cellphones among other sources. CCTV footage certainly can be evidence and, even if no recognized method is used, is often considered forensic*.
CCTV is a form of forensic evidence with one important difference–its retrieval and interpretation happens outside the scientific laboratory…CCTV footage, like other forms of forensic evidence, does not provide an absolute truth.
Evidence retrieval often happens outside the laboratory; that’s what crime scenes are. Interpretation sometimes happens outside the laboratory as well. But CCTV is a type of forensic* evidence that is frequently retrieved and interpreted by non-forensic experts, like police and prosecutors. What could go wrong?
Problems with CCTV Evidence
Well, as you might expect, a lot. A recent study, by Fiona Brookman and Helen Jones, of homicide cases in the UK where CCTV was used demonstrated that:
Because police may lack the skills, training, or equipment to recover the footage in time, CCTV becomes inaccessible or lost. CCTV is often deleted within three weeks of being recorded or over-written within 7 to 10 days.
Managers of a camera system may not be able to access the footage (like having to take a bus out of service to download it), the amount of data precludes easy downloading, or format issues. Even when footage is retrieved, officers may not be available to view it.
Footage that exonerates a suspect may not be disclosed to the defense.
The images may be of blurry or poor quality.
Police may need to call on an expert for assistance but may not have one available or have guidance of when to do so. This runs the risk of the officer deciding they can interpret footage themselves, without training or experience.
Some officers are thought to be “super-recognizers” (people who are assumed to be better at identifying people than others) and are repeatedly called in to interpret images. No robust measures exist for determining if someone is a super-recognizer or not. If these officers are called to court as being “super,” their testimony may have undue influence with the jury.
What the jury sees is a processed, edited selection made by the police and prosecutor. Or by the defense, for that matter. Juries don’t necessarily see the original footage or know what’s been edited and how.
As a digital expert noted on Twitter,
Did a case recently. (1) CCTV was broken (IR light not working) (2) significant areas not covered (3) collection of evidence wrong in _several_ ways ... Without getting into actually questioning the footage.
Sure, there may be problems with any kind of evidence, like poor (or no) collection, contamination, what have you, so why worry about CCTV? It’s not that CCTV is any different from other kinds of evidence, it’s that we’re putting all of our evidential eggs in one digital basket.
Digital is the new DNA
When DNA hit the forensic landscape, it created shockwaves that resonate to this day (think investigative genetic genealogy). All the focus and money went to this amazing new technology and method: $1 billion over 5 years by the U.S. government alone. Laboratories created new budgets and diverted old ones; initially, some serology staff were retrained to process biological evidence for DNA analysis. Today, DNA remains one of the most requested services of forensic providers. What happened to the rest of the laboratory, however? Some disciplines took hits, like fibers, soil, glass, paint, handwriting, documents, and other “old school” methods. Articles ringing with the sturm und drang of the loss of the traditional methods were regularly published without much data. Based on recent data from Project FORESIGHT show that submissions per 100,000 population served for trace evidence and documents are down while digital and DNA are up:
A longer analysis is worthwhile (Project FORESIGHT has data going back to 2008) and that may be part of a future post. Nevertheless, resources have been diverted to DNA and digital, including CCTV, and the remainder of the services suffer. Whether it is a chicken vs. egg (sorry) causation argument is a larger question and one worth pursuing. But the mentality has been around for some time. This, from testimony at a 2016 UK House of Commons (thanks to Tiernan Coyle):
As Tiernan put it:
Arguably, CCTV, like other digital evidence, has been as fetishized as DNA has been: One evidence to convict them all. Why bother with all that “ancient” stuff, like fibers and documents, when we have CCTV? In the article by Brookman and Jones, they listed the kinds of forensic science* and technology used to charge suspects:
Look familiar? CCTV and DNA are the highest out of eight non-digital methods and six digital ones (ANPR = automatic number plate recognition). Brookman and Jones warn:
Given the prominence of CCTV in homicide investigation, and the grave implications of investigative errors, it is time for the CJS to acknowledge the socially constructed nature of CCTV evidence and guard against its misuse.
That’s true but what about the idea that the CJS consistently puts its full faith in the “next big thing” and ignores the “rest of the lab.” Bertillonage was the rage until fingerprinting came along. Serology seduced the CJS until DNA exploded into forensic land. Now digital threatens and we’re going to do the same thing: Bleed limited budgets and divert monies to the shiny new thing. Much digital work is done-- unaccredited and unsupervised--by police officers, which is worrisome for so many reasons. When we ignore a balanced approach to evidence, the public and the innocent suffer.