Prevention of Terrorism (Temporary Provisions) Act 1989

2 (1) Any person who has arrived in, or is seeking to leave, Great Britain or Northern Ireland by ship or aircraft may be examined by an examining officer for the purpose of determining—

(a) whether that person appears to be a person who is or has been concerned in the commission, preparation or instigation of acts of terrorism to which this paragraph applies; or

(b) whether any such person is subject to an exclusion order; or

(c) whether there are grounds for suspecting that any such person has committed an offence under section 8 of this Act.

(2) This paragraph applies to—

(a) acts of terrorism connected with the affairs of Northern Ireland; and

(b) acts of terrorism of any other description except acts connected solely with the affairs of the United Kingdom or any part of the United Kingdom other than Northern Ireland.

(3) An examining officer may—

(a) examine any person who is entering or seeking to enter or leave Northern Ireland by land from, or to go to, the Republic of Ireland for the purpose of determining whether that person is such a person as is mentioned in any of paragraphs (a) to (c) of sub-paragraph (1) above;

(b) examine any person found in Northern Ireland within a distance of one mile from the border with the Republic of Ireland for the purpose of ascertaining whether he is in the course of entering or leaving Northern Ireland by land;

(c) examine any person entering Northern Ireland by train when he arrives at the first place where the train is scheduled to stop for the purpose of allowing passengers to alight.

(4) The period of a person’s examination under this paragraph shall not exceed twenty-four hours unless he is detained under paragraph 6 below, and may only exceed twelve hours if an examining officer—

(a) has reasonable grounds for suspecting that the person examined is or has been concerned in the commission, preparation or instigation of acts of terrorism to which this paragraph applies; and

(b) gives him a notice in writing requiring him to submit to further examination.

(5) In sub-paragraph (1) above the reference to arrival by ship or aircraft includes a reference to arrival as a transit passenger, member of the crew or other person not seeking to enter Great Britain or Northern Ireland.