The ICO exists to empower you through information.

These subsections of the exemption apply to information whose disclosure might affect either criminal or civil law enforcement.

In practice, there won’t always be a clear dividing line between each sub-section. If potential criminals believe that they can avoid being apprehended or prosecuted, they are more likely to commit a crime. Equally, it is a criminal offence to evade tax or to enter the UK illegally. Therefore, any information whose disclosure could make it harder to enforce such laws will probably also make it easier for someone to commit a crime.

If you rely on more than one sub-section of the exemption and we receive a complaint, you will need to provide clear reasoning as to why each subsection applies.

Section 31(1)(a) – the prevention or detection of crime

Section 31(1)(a) covers all aspects of the prevention and detection of crime. It could apply to information on general policies and methods adopted by law enforcement agencies, as well as information about specific investigations. For example, it could apply to the police’s procedures for collecting forensic evidence or to HM Revenue and Customs’ procedures for investigating tax evasion.

You don’t need to have responsibilities to investigate crime yourself to rely on this part of the exemption. You could use it to withhold copies of information provided to a law enforcement agency as part of an investigation. You could also use it to withhold information that would make anyone, including yourself, more vulnerable to crime. An example could be disclosing your own security procedures, such as alarm codes.

You also don’t have to demonstrate that you are holding the information for the purpose of preventing or detecting crime. You only have to demonstrate that disclosing the information could harm efforts to prevent or detect crime.


In Yiannis Voyias v Information Commissioner and the London Borough of Camden (EA/2001/0007 23 January 2013), the First Tier Tribunal upheld the council’s decision to withhold the addresses of empty houses under section 31(1)(a).

The information was collected for council tax purposes and to inform the council’s policies aimed at returning empty homes to the housing market. However, the First Tier Tribunal was satisfied that, if disclosed, squatters could use the information.

Although squatting was not (at that time) a criminal offence, squatting is associated with criminal damage, for example when entering and securing properties. Criminal gangs who stripped buildings of valuable materials and fixtures could also use the list to target properties.

Section 31(1)(b) – the apprehension or prosecution of offenders

This subsection overlaps with both 31(1)(a) and 31(1)(c). It could potentially cover information on general procedures about apprehending offenders or the process for prosecuting offenders. It also protects information about specific prosecutions, ie you can rely on it even if you do not have specific powers or duties to apprehend or prosecute offenders.

Section 31(1)(c) – the administration of justice

The administration of justice is a broad term. It applies to the justice system as whole. Amongst other interests, the exemption protects information whose disclosure could undermine particular proceedings. There is an overlap between section 31(1)(c) and section 31(1)(b) which protects the process for prosecuting offenders.


Decision notice FS50209828 considered a request for the details of forensic evidence which the Northern Ireland Office (NIO) had examined in relation to a double murder. At that time, the NIO provided a forensic science service to the police. Two defendants were awaiting trial for the murders.

The NIO explained that, although they had collected a large amount of forensic evidence, some of it would prove irrelevant and other evidence could be misleading if not presented objectively. The NIO was concerned that placing the information in the public domain before the trials were complete would, in effect, interfere with the right to a fair trial. The Information Commissioner was satisfied that section 31(1)(c) was engaged.

The NIO also argued that disclosing the information could assist those responsible for the murders to cover their tracks. This, again, would undermine the administration of justice. This argument would also engage section 31(1)(b) – the prosecution of offenders.

Finally, the NIO presented a broader argument: that the disclosure would help criminals adopt techniques for avoiding detection in the future. Again this argument would support the application of section 31(1)(b).

This case also demonstrates how section 31 can complement the protection provided by section 30. If the police received the same request, they could have applied section 30(1)(a)(i) to withhold information obtained for the purposes of a criminal investigation which they had the duty to conduct. The NIO could not rely on section 30 because they did not have the required duty to investigate. However, section 31 provided protection for the same information in their hands.

Section 31(1)(c) can also protect a wide range of judicial bodies, such as courts (including coroner’s courts) and tribunals, from disclosures that could interfere with their efficiency, effectiveness or their ability to conduct proceedings fairly. This includes harm to the administrative arrangements for these bodies, the appointment of magistrates and judges, or arrangements for the care of witnesses. It would also cover any disclosures that could interfere with the execution of process and orders in civil cases.

Anything that could make it harder for the public to access the justice system may also engage the exemption.


In decision notice IC-200766-T5H8, the Commissioner considered tax records, held by the National Archives (TNA), of four deceased members of the royal family.

TNA argued that the High Court had recently made an order determining when royal wills would be sealed and in what circumstances previously-sealed wills would be made public. Because the tax records covered the contents of those wills, disclosing the information would undermine the Court’s order and thereby prejudice the administration of justice.

TNA was unable to rely on section 44(1)(c) of FOIA (contempt of court) because the court order only concerned the will documents themselves, not the information they contained. However, the Commissioner accepted that disclosing the tax records would make the order redundant. It would remove matters from the High Court’s jurisdiction that they had explicitly reserved for themselves.

In addition, the Commissioner accepted that disclosure would have interfered with proceedings about the will of the recently deceased Prince Philip. These were ongoing in the Court of Appeal at the point the request was responded to. Therefore, section 31(1)(c) was engaged.

Section 31(1)(d) – the assessment or collection of any tax or duty or any imposition of a similar nature

The phrase “tax, duty or imposition of a similar nature” is a broad term. It captures not only national taxation (such as income tax, corporation tax or VAT) but also National Insurance contributions, local taxation (such as council tax) and duties paid on other goods (such as petrol, alcohol and imported goods). HM Revenue and Customs (HMRC) is the most obvious public authority that needs to use the exemption, but you do not need to have tax collection functions yourself to rely on this exemption.


ICO decision notice FS50089784 found that, under section 31(1)(d), HMRC could refuse a request for information on their investigation into a particular company’s corporation tax affairs.

HMRC argued that the information would not only harm their current investigation, but that some of the information would reveal their general approach to such investigations. This would make it harder to investigate similar cases in the future.

The exemption protects information whose disclosure could undermine the collection of tax from a particular person, or help them evade tax. It would also apply if disclosing the information could promote tax avoidance.


In Paul Doherty v Information Commissioner and Her Majesty’s Revenue and Customs (EA/2011/0202 25 January 2012) the requested information concerned loopholes in inheritance tax.
The appellant argued, at paragraph six, that organisations should only use the exemption to prevent people evading tax (which is illegal). They should not use the exemption to prevent people exploiting a legal tax loophole to avoid tax. In dismissing this argument the First Tier Tribunal explained that they were satisfied that disclosing the information would result in, “less tax being lawfully due than would otherwise have been the case” and that this was sufficient to engage the exemption.

You could also use this exemption to withhold information that could make it easier to disrupt the online collection of taxes.

HMRC also undertakes operations on the ground, for example to prevent tobacco smuggling or the illegal use of red diesel. Information that frustrates such operations could engage section 31(1)(d).

Section 31(1)(e) – the operation of immigration controls

You can use this exemption where disclosure could undermine:

  • physical immigration controls at points of entry into the UK;
  • measures taken to avoid people travelling to the UK if they do not have the correct paperwork; or
  • efforts made to deport those with no right to remain in the country.

It could also protect information about issuing and approving work permits or the processing of asylum applications.


Decision notice FS50286261 considered a request to the Home Office for information about the flight arrangements for the deportation of failed asylum seekers. By the time of the request, the asylum seekers had already been deported. The Home Office was concerned that disclosing the information could undermine future deportations. The Commissioner accepted that this was an interest protected by section 31(1)(e).

However, he found that it would not be harmful to disclose the ratio of guards to asylum seekers. This was because the Home Office would tailor the security arrangements for any flight to the particular circumstances of the deportation. Therefore, revealing the arrangement for one flight would not provide meaningful intelligence to anyone wanting to obstruct future deportations.

It is not enough for the information to merely relate to an interest protected by section 31(1)(e). Its disclosure must also at least be likely to harm that interest. This is true for all the subsections of section 31. The onus is on you to explain how that harm would arise and why it is likely to occur.



Decision notice IC-81555-F6Y6 considered another request to the Home Office, this time for information about aerial surveillance. On this occasion, the Home Office successfully argued that information about their surveillance capabilities would, if released, help those attempting to evade border controls.

Section 31(1)(f) – the maintenance of security and good order in prisons or other institutions where persons are lawfully detained

The term “security and good order” includes, but is not limited to, both external and internal security arrangements. It will also protect any information likely to undermine the orderly running of these institutions from disclosure.

The “other institutions” referred to includes:

  • Young Offender Institutions;
  • secure hospitals;
  • secure training centres,
  • Local Authority secure units; and
  • immigration removal centres.


In decision notice FS50383346, the Commissioner accepted that a floor plan of HMP Belmarsh was exempt. This is because someone could use it if they were planning an escape.



In decision notice IC-180847-H4Q4, a requester asked the Home Office to provide details of the CCTV monitoring systems used in immigration removal centres. The Commissioner agreed that disclosing such information would be likely to make it easier for people to circumvent security measures at those centres. Consequently, this could undermine the maintenance of security and good order in those institutions.