2.
The appeals now before the House are a later stage of the
proceedings in which the House gave judgment in December 2004: A
and others v Secretary of State for the Home Department, X and another
v Secretary of State for the Home Department [2004] UKHL 56, [2005]
2 AC 68. In their opinions given then, members of the House recited the
relevant legislative provisions and recounted the relevant history of the
individual appellants up to that time. To avoid wearisome repetition, I
shall treat that material as incorporated by reference into this opinion,
and make only such specific reference to it as is necessary for resolving
these appeals.
The Anti-terrorism, Crime and Security Act 2001
3.
The 2001 Act was this country’s legislative response to the grave
and inexcusable crimes committed in New York, Washington DC and
Pennsylvania on 11 September 2001, and manifested the government’s
determination to protect the public against the dangers of international
terrorism. Part 4 of the Act accordingly established a new regime,
applicable to persons who were not British citizens, whose presence in
the United Kingdom the Secretary of State reasonably believed to be a
risk to national security and whom the Secretary of State reasonably
suspected of being terrorists as defined in the legislation. By section 21
of the Act he was authorised to issue a certificate in respect of any such
person, and to revoke such a certificate. Any action of the Secretary of
State taken wholly or partly in reliance on such a certificate might be
questioned in legal proceedings only in a prescribed manner.
4.
Sections 22 and 23 of the Act recognised that it might not, for
legal or practical reasons, be possible to deport or remove from the
United Kingdom a suspected international terrorist certified under
section 21, and power was given by section 23 to detain such a person,
whether temporarily or indefinitely. This provision was thought to call
for derogation from the provisions of article 5(1)(f) of the European
Convention, which it was sought to effect by a Derogation Order, the
validity of which was one of the issues in the earlier stages of the
proceedings.
5.
Section 25 of the Act enables a person certified under section 21
to appeal to SIAC against his certification. On such an appeal SIAC
must cancel the certificate if “(a) it considers that there are no
reasonable grounds for a belief or suspicion of the kind referred to in
section 21(1)(a) or (b), or (b) it considers that for some other reason the
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