Comparing sections 30 and 31 - the investigations and law enforcement exemptions

If someone requests information about investigations or law enforcement, you may need to consider whether it’s exempt under section 30 or section 31 of FOIA. These exemptions can cover information relating to civil proceedings, as well as criminal investigations and offences, but there are important differences in how they apply and who can use them.

If the information is the type that’s covered by section 30, you cannot use section 31 to withhold it. You can only rely on exemptions from both sections 30 and 31 in certain circumstances, including where you decide to neither confirm nor deny whether you hold the information.

Remember that both sections contain multiple exemptions. You’ll need to decide which specific subsection applies.

Use this table to help decide whether section 30 or 31 is relevant.

	Section 30 FOIA	Section 31 FOIA
Name of sections	Investigations and proceedings conducted by public authorities	Law enforcement
Who can use the exemptions under these sections?	Only public authorities with the duty or specific powers to carry out investigations or proceedings.	Any public authority.
When can exemptions from these sections be engaged (when will they apply)?	It covers information that’s held for the purposes of a specific investigation or prosecution, relates to obtaining information from confidential sources, or both.	Use s31 when the information isn’t covered by s30 but you can show that disclosure would, or would be likely to, prejudice law enforcement activities (see below).
How do we explain prejudice (harm)?	You don’t need to show prejudice to use s30, although it can be relevant to your public interest test (see below).	Firstly, identify which legal process, function or investigations you believe will be harmed, from the activities covered by s31(1) and 31(2). You may also need to identify which public authority has the relevant function, if it’s not your own organisation. Secondly, explain how and why harm will occur to those activities. Finally, explain if prejudice is likely to occur if the information is disclosed.
If an exemption is engaged, do we then need to do a public interest test?	Yes	Yes
What sort of public interest arguments are likely to be relevant?	Protecting your ability to carry out an effective investigation or prosecution. Protecting your confidential sources.	Protecting an organisation's ability to carry out the law enforcement activity or activities you've identified from s31(1), s31(2) or both.
	Also consider: the extent of the harm you envisage the stage of the process what's in the public domain; and the significance of the information. You can only consider the consequences of the harm that the exemption guards against.
	Remember to weigh these arguments against the public interest in the disclosure of the requested information and in transparency. There is a public interest in disclosing information that holds law enforcement bodies to account.
When should we use NCND (neither confirm nor deny)?	You believe confirming or denying that you hold the information would harm the effective conduct of an investigation, or other proceeding, which you have the duty or power to conduct.	You believe confirming or denying you hold the information would harm the effective conduct of an investigation, or other law enforcement activity, by you or another public body.
Which NCND should we use: s30(3) or s31(3)?	If you’re a PA that can use s30 (see above), you may be able rely on both section 30(3) and 31(3) to refuse to confirm or deny whether you hold the same information.	If you can’t use s30, you can still use s31(3) to refuse to confirm or deny whether you hold the requested information.
	Remember that you still need to do a public interest test to decide if it’s in the public interest to refuse to confirm or deny you hold the information.