Aviation (Preclearance) Act 2009
In-transit preclearance: control of aliens.
12.— (1) Subject to subsection (2) , a person who lands at an airport in the State for the purposes of in-transit preclearance, shall not, for the purposes of the Aliens Act 1935 and the Immigration Act 2004, be deemed to have arrived at a frontier of the State.
(2) A person who—
( a) lands at an airport in the State for the purposes of in-transit preclearance, and
( b) is refused preclearance to travel onwards to the United States,