Curfew tags – the gory details

In previous posts I told the story of how Britain’s curfew tagging system can fail. Some prisoners are released early provided they wear a tag to enforce a curfew, which typically means that they have to stay home from 7pm to 7am; some petty offenders get a curfew instead of a prison sentence; and some people accused of serious crimes are tagged while on bail. In dozens of cases, curfewees had been accused of tampering with their tags, but had denied doing so. In a series of these cases, colleagues and I were engaged as experts, but when we demanded tags for testing, the prosecution was withdrawn and the case collapsed. In the most famous case, three men accused of terrorist offences were released; although one has since absconded, the other two are now free in the UK.

This year, a case finally came to trial. Our client, to whom we must refer simply as “Special Z”, was accused of tag tampering, which he denied vigorously. I was instructed as an expert along with my colleague Dr James Dean of Materials Science. Here is my expert report, together with James’s report and addendum, as well as a video of a tag being removed using much less than the amount of force required by the system specification.

The judge was not ready to set a precedent that could have thrown the UK tagging system into chaos. However, I understand our client has now been released on other grounds. Although the court did order us to hand back all the tags, and fragments of broken tags, so as to protect G4S’s intellectual property, it did not make a secrecy order on our expert reports. We publish them here in the hope that they might provide useful guidance to defendants in similar cases in the future, and to policymakers when tagging contracts come up for renewal, whether in the UK or overseas.

9 thoughts on “Curfew tags – the gory details

  1. This reminds me of the Challenger disaster – a manufacturer that keeps saying everything is ok, until Richard Feynman simply puts a rubber O-ring into a cold water and shows that it is actually not elastic any more.

    How simple does a prove have to be so that one does not need an expert to understand it. This actually makes me think whether judges should be required to have a degree in logic or another suitable mathematical discipline to understand and challenge chains of arguments provided by expert witnesses.

  2. Another thing that might be noted is that polycarbonate’s chemical resistance is woefully low. A splash of acetone (found in such things as nail polish remover) commonly causes it to “craze”, instantly developing a crack pattern. (This only happens when there are pre-existing stresses manufactured into the material, but that is common in molded items.) Besides being a common chemical, acetone is also naturally produced by the body, in some cases in noticeable concentrations (google “acetone breath” for details).

  3. Can someone at Cambridge fix the Content-Type header that your web server is sending with the video?

    It’s currently “text/plain”, which is making my web browser try to display it as if it were text, which makes the browser slow down and display a very long page full of gibberish. I think it should be “video/mp4”

  4. Better yet, fire it on Vimeo, YouTube or another hosting site. I didn’t realise what I was clicking through to, and it actually crashed Firefox for me.

  5. Sorry for the inconvenience, guys!

    I put the video on youtube and edited the post to link to that version

  6. I remember reading in some newspaper (might have been the Daily Mail) a few years back that people who were tagged simply put on several pairs of thick socks when getting tagged. They then removed the socks and simply slid the tag off, then absconded. Then there’s this:

Leave a Reply

Your email address will not be published. Required fields are marked *