sign a conclusive certificate certifying exemption form s 7(1) for such
purpose, subject to an appeal by a person directly affected to appeal
against the certificate to the Information Tribunal, which has power to
quash the certificate.
The NCND Policy and National Security
15. In his written reasons for signing the certificate the Secretary of State
referred in paragraphs 4 and 5 to considerations underpinning the NCND
policy invoked in this case in respect of subject access requests. The
Respondent's functions relate to the protection of national security.
Secrecy is essential to the work of the Security Service. It is needed to
secure the co-operation of individuals. Investigations are undertaken
covertly. Techniques used would lose much of their effectiveness if it
became known when and how they are used. The NCND policy is needed
to help to preserve secrecy.
"5.3 The Government applies the [NCND] policy to Security Service
investigations and to suggestions of whether a particular individual
or group is or has been under investigation. To ask whether the
Security Service holds personal data on an individual often
amounts to asking whether there is or has been an investigation.
5.4 By logical extension, the policy must apply even if no
investigation has taken place. If the Security Service said when it
did not hold information on a particular person, inevitably over time
those on whom it did hold information would be able incrementally
to deduce that fact. Not least because they would not receive the
same assurance given to others."
16. If individuals, who are intent on damaging national security,, could
discover that they are not the subject of interest, then they could undertake
their activities with increased confidence and vigour. If they could discover
that they are the subject of interest, they could take steps to thwart the