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Online identifiers in security logging and monitoring

Parent topic: Logging and monitoring

Related information

Logging and monitoring


It can sometimes be counter-intuitive to think of IP addresses, cookies, and log data as personal data. However there are good reasons why it is important fort he Ministry of Justice (MoJ) during design, implementation, and operation of MoJ online services. Put simply, it is easiest for the MoJ to assume that any information captured and processed through public-facing services might contain personal information, and to protect this information accordingly.

What are online identifiers?

Online identifiers are anything that could be used to track someone as they interact with MoJ online services. This can include, for example:

  • IP addresses.
  • Cookies that the MoJ or authorised 3rd parties set on devices.
  • Information placed into local storage on devices.
  • Usernames or other IDs associated with MoJ services.
  • Third-party authentication tokens.

Online identifiers could also include metadata captured about a device interacting with MoJ services if this information is sufficiently different to allow devices to be reliably identified.

Why are online identifiers treated as personal data?

If there is any way to tie an online identifier to an individual, then that identifier needs to be treated as though it is personal data.

The way this mapping might be achieved is unimportant.

It could be because the user later provides personal data to the MoJ as part of using a service, and in doing so provides a link between all of the activities that their IP or session cookie has done with their identity.

There might also be a legal route available to the MoJ to determine the identity behind an identifier. For example, by making a lawful request to an ISP to uncover the person associated with a dynamic IP address at a particular time.

For more information on this, refer to the Information Commissioner’s Office (ICO) key definitions, and “Recital 30” from the Article 29 Working Group. There is also an informative article here.

What does this mean for MoJ services?

It is important to think carefully about:

  • What metadata is captured during a user’s interaction with MoJ services.
  • How long information is retained.
  • Who has access to the information.

MoJ privacy notices on services must be clear about the information captured as part of a user’s interaction. This includes “anonymous” interactions, such as simple browsing information about the services. Metadata like this must be included in the scope of privacy impact assessments for MoJ services.

Note: Theoretically, privacy notices are only mandatory for externally-facing services. They are not required for internal services. However, it is undoubtedly good practice - and highly recommended - to apply the same approach, for consistency.

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