As might be expected, FOIA contains a specific exemption designed to safeguard national security, see the exemption provided for under s. 24. In essence, the s. 24 exemption is engaged if the exemption ‘is required for the purposes of safeguarding national security’. Perhaps somewhat surprisingly, the section 24 exemption is a qualified exemption (see s. 2(3) FOIA). This means that, even if the exemption is required in respect of particular information to safeguard national security, the information may still be disclosable on an application of the public interest test provided for under s. 2 FOIA. In Kalman v IC & Department for Transport (EA/2009/0111), the Tribunal was for the first time called upon to consider the substantive application of s. 24 (i.e. how it applied to specific information – cf. Baker v IC & Ors EA/2006/0045, where the tribunal considered the application of the national security exemption in the context of the duty to confirm or deny whether the information was held). The Kalman case involved an application for disclosure of information relating to airport security arrangements. The DfT refused to disclose the information on the basis that there was a real risk that the information, if disclosed, would be exploited by terrorist organisations. The Commissioner largely rejected Mr Kalman’s complaint against the DfT’s decision. Mr Kalman appealed to the Tribunal. There were two issues at stake in the appeal. First, whether s. 24 was engaged in respect of the disputed information and, second, if it was engaged, whether the public interest balance nonetheless weighed in favour of disclosure.

During the course of the hearing, the DfT conceded that some of the disputed information could be disclosed, not least because it was already effectively the stuff of public knowledge. The Tribunal went on to hold that there was other information which ought to have been disclosed for much the same reason. With respect to the remainder of the information, the tribunal accepted that s. 24 was engaged and that the public interest weighed in favour of maintaining the exemption. Notably, the tribunal held that the nature of the risk posed by the disclosure was so serious in this case (i.e. potential significant loss of life due to terrorists exploiting weaknesses in the airport security system) that, even if the risk was relatively slight, there would have to be an extremely strong public interest in disclosure to avoid the information being lawfully withheld. In reaching this conclusion, the tribunal adopted a similar analysis to the one which it had previously adopted in PETA v IC & Oxford University (EA/2009/0076) (case involving the application of the health and safety exemption in a case involving risk of attack by animal extremists).