The ICO exists to empower you through information.

Even if you are withholding certain information, you must usually still tell the requester that you hold it. However, you can rely on section 31 if just telling the requester that you hold the information could affect your, or another organisation’s, ability to enforce the law.

Section 31(3) states:

31.—(3) The duty to confirm or deny does not arise if, or to the extent that compliance with section 1(1)(a) would or would be likely to, prejudice any of the matters mentioned in subsection (1).

You can rely on both section 30(3) and 31(3) to refuse to confirm or deny holding the same information. You would need to ensure that you meet the conditions for both exemptions.

All the parts of the exemption that can be used to withhold information can be used to refuse to confirm or deny that information is held – however, in practice, you only would refuse to confirm or deny that you held information in a small number of scenarios.

Avoid confirming the existence of, or subjects of, investigations

Confirming that a particular investigation is (or is not) active, or confirming who or what is (or is not) the subject of a particular investigation can harm the investigation’s outcome. If a person or organisation knows that they are under investigation, but have not been formally contacted, they may then have an opportunity to destroy or conceal key evidence. This harms the ability of that investigation to reach a fair conclusion.

Where a request identifies a person or an organisation as the possible subject of an investigation, or particular lines of enquiry a public authority could be pursuing, there is a strong chance that confirming the information’s existence could harm that investigation.


Decision notice FS50150268 dealt with a request made to the Office of Fair Trading (OFT). The requester asked for information about a particular company that he believed the OFT was investigating.

The OFT relied on section 31(3) to refuse to confirm or deny whether they held any information. This was because confirmation or denial would reveal whether or not the company was under investigation. This in turn would harm their ability to determine whether the company in question (or companies in general) had complied with the law.

The OFT argued that if they were to routinely confirm or deny whether they held information on any named company, this would provide a means for any company which suspected they were under investigation to have this confirmed. The company could then take steps to conceal evidence.

Clearly, confirming an investigation had taken place would not be harmful if there had already been official acknowledgement of the investigation’s existence.

The example above demonstrates why you should be careful when deciding whether it is appropriate to confirm or deny that you hold particular information. You need to ensure that you are doing so (or refusing to do so) consistently.

When deciding whether to deny that you hold information about a law enforcement activity, you should consider whether you would also have been prepared to confirm that you held the information. If you only refuse to confirm or deny in situations where you are, in fact, holding the information, then this will become apparent over time and defeat the exemption’s purpose.

You should also consider the mosaic effect. If you were to routinely confirm or deny that you held particular information, would that show a broader pattern about your work over time?

Avoid revealing techniques or capabilities being deployed

Confirming or denying that you hold information about the use of particular investigative techniques could also harm the work of law enforcement agencies. This applies if that information is not already in the public domain.


In decision notice IC-172328-J7J3, the Commissioner upheld West Yorkshire Police’s decision to refuse to confirm or deny whether they held details of a contract for social media monitoring software, the terms of that contract and what they used the software for.

The Commissioner agreed that confirming that the police held the information would reveal details of that police force’s capabilities. By contrasting West Yorkshire Police’s response with the responses given by other forces (if they were all to confirm or deny whether they held such information) would also reveal a broader picture of capability amongst police forces. This might indicate where a person was more likely to commit a crime undetected.

When we investigate a complaint about the application of section 31(3), it is usually possible to make a decision on its use without knowing whether you hold the information. However, we do reserve the right to be informed whether or not you hold the information, to make a decision about whether or not the exemption would apply.