Terrorism Act 2000
In order to use powers under the Terrorism Act, officers must have some suspicion that you specifically are involved in terrorism and that searching you may reveal evidence of this.
Please note that section 44 of this act was repealed after it was ruled to be unlawful by the European Court of Human Rights in 2010. It had previously given officers the blanket power to search anyone they wanted to without needing any suspicion that they individual was involved in terrorism. The power was, perhaps unsurprisingly, misused by officers to search people from ethnic minorities and those attending demonstrations, amongst others.
Section 43 – Search of persons.
(1)A constable may stop and search a person whom he reasonably suspects to be a terrorist to discover whether he has in his possession anything which may constitute evidence that he is a terrorist.
(2)A constable may search a person arrested under section 41 to discover whether he has in his possession anything which may constitute evidence that he is a terrorist.
(3)A search of a person under this section must be carried out by someone of the same sex.
(4)A constable may seize and retain anything which he discovers in the course of a search of a person under subsection (1) or (2) and which he reasonably suspects may constitute evidence that the person is a terrorist.
(5)A person who has the powers of a constable in one Part of the United Kingdom may exercise a power under this section in any Part of the United Kingdom.