Exemption Index logoFOIMan takes on the military might of the FOI exemption designed to avoid conflict with the UK’s defence.



There can be few things more sensitive in government than the defence of the country. It is not surprising that FOI contains an exemption protecting information that might place that defence at risk.

There isn’t however, a vast amount of case law in relation to this exemption. Perhaps this is because in many cases when the exemption might be applied, the information also tends to fall under other exemptions. The case law that does exist contends that there is a substantial public interest in information being withheld where the exemption applies.

One effect of this exemption is that we are not currently allowed to know whether the government has a ray gun or phaser in development. So we’ll have to wait a while before knowing whether Star Trek’s phasers or the Death Star’s planet destroying capability will become reality.

Information affected

Any information which if disclosed would or would be likely to prejudice the defence of the British Islands or of any colony, or the capability, effectiveness or security of the armed forces, not just of the UK, but also of its allies.

Things that FOI Officers need to know

  • The ICO suggests that prejudice in this context means that disclosure might assist an enemy.
  • The exemption covers prejudice not just to UK troops, but also their allies; the ICO’s guidance suggests that this will include formal as well as informal alliances (the guidance mentions as an example the alliance of forces that went into Afghanistan in 2001).
  • Obviously this exemption will most often be used by the Ministry of Defence or its agencies, but the ICO makes clear that other authorities may well have cause to cite it – for example in relation to emergency planning.
  • The ICO suggests that the greater the risk of prejudice, the greater the public interest in withholding the information.
  • There is an exceptionally strong public interest in maintaining the safety and effectiveness of the armed forces (see para 53 of linked Tribunal decision).
  • Authorities can refuse to confirm or deny whether information is held if confirmation would or would be likely to prejudice defence – on one celebrated occasion, the Tribunal upheld the Ministry of Defence’s right not to confirm whether or not it held information on the development of a ray gun! (Or “direct energy weapon” to use the official parlance).

Things that requesters need to know

  • Just because it’s about defence matters, it doesn’t mean that disclosure would or would be likely to cause prejudice. The public authority should have explained how disclosure might cause the prejudice in the specific case.
  • There’s always going to be a strong public interest in preserving the safety and effectiveness of the armed forces – so you’ll need a good argument as to why it is in the public interest to disclose the information (see para 69 of the linked Tribunal decision).
  • The ICO guidance on section 26 suggests that arguments in favour of disclosure will include: furthering public understanding and participation; promoting transparency and accountability in relation to decisions and spending; revealing health and safety issues.

Essential case law

Recommended reading

Paul Gibbons is delivering a new workshop for Act Now Training this Autumn looking at all of the FOI Exemptions – visit the Act Now Training website for further details.

One Comment

  1. The comment that the Ministry of Defence would use this exemption is the tip of the iceberg as the documents would be in quite a lot of Government files and so you would expect that the Prime Minister’s Office, Foreign and Commonwealth office and Treasury would (or should) be caught by the same exemption to ensure that was being protected was consistent.

    David Matthew

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