IP Address Resolution Errors
I am concerned by the increasing number of errors that occur when public authorities try to
resolve IP addresses. These have resulted in the wrong people being arrested for extremely
serious crimes. I am devoting a chapter of my report to this issue in order to raise the profile
of this issue within public authorities and among victims and their legal representation.

IP Address Resolutions
IP (Internet Protocol) addresses tell the internet where, physically, to send information.
As a result, IP addresses can usually be used to link specific online activity to a specific
physical device (i.e. a specific router or phone), which would often be linked to a specific
location or individual. However, unlike a real physical address, the Communications
Service Providers (CSPs) can easily reassign IP addresses, and it often makes sense for
them to do so. For example, many CSPs have more customers than IP addresses, so they
only assign IP addresses to active customers (those online). This means that when you
log off, the IP address you were using is assigned to the next person. You may well have a
different IP address when you log back in again. CSPs also sometimes change customers’
IP addresses for security reasons. Changing your IP address makes it harder for ‘cybercriminals’ to find you. More recently, CSPs have been routing multiple users through the
same IP address. This saves on the number of IP addresses used but makes it hard to
know which of those users is responsible for any activity coming through that address.
All of this means that turning an IP address into a specific location is increasingly complex.
To link an IP address to a CSP’s customer’s address, the public authority needs to provide
the time when online activity occurred. There is significant variation in how time is
recorded online, in ‘date stamps’. For example: 1 in the morning on the first of January
2017 could be represented as: 201701010100; 1.00 1-Jan-17; or 0100 1 January 2017. In
addition, not all of these systems record the time zone.

Errors
All of this greatly increases the risk of error. Most of these are transcription errors (a
number is typed in incorrectly). Based on the complexity set out above, it is easy to
see why. But errors can also be caused by other issues. The impact of these errors has,
in some cases, been enormous. People have been arrested for crimes relating to child
sexual exploitation. Their children have been taken into care, and they have had to tell
their employers. On confirmation of the error, all the power of the state, which comes
into force to protect children, needs to be turned around and switched off. I have a great
deal of admiration for Nigel Lang, who was arrested in error in these circumstances, for
having had the courage to highlight this issue in the media.
By way of balance, it is worth highlighting that there is a reason why serious IP address
resolution errors are relatively more common in relation to child sexual exploitation cases
than other crimes. Public Authorities are understandably unwilling to take the risk of
exposing children to paedophiles. As a result, where an IP address resolution shows a
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