100.—(1) Where a safety critical worker is arrested under section 99, a member of the Garda Síochána may, at a Garda Síochána station, at his or her discretion, do either or both of the following:

(a) require the worker to provide, by exhaling into an apparatus for determining the concentration of alcohol in the breath, 2 specimens of his or her breath and may indicate the manner in which he or she is to comply with the requirement,

(b) require the worker either—

(i) to permit a designated medical practitioner to take from the worker a specimen of his or her blood, or

(ii) at the option of the worker, to provide for the designated medical practitioner a specimen of his or her urine.

(2) If the medical practitioner referred to in subsection (1)(b) states in writing that he or she is unwilling, on medical grounds, to take from the safety critical worker a specimen of the worker's blood or be provided by the worker with a specimen of the worker's urine, the member may make a requirement of the worker under subsection (1)(b) in relation to the specimen other than that to which the first requirement related.

(3) Subject to section 108, a person who refuses or fails to comply immediately with a requirement under subsection (1)(a) is guilty of an offence.

(4) Subject to section 108, a person who, following a requirement under subsection (1)(b)—

(a) refuses or fails to comply with the requirement, or

(b) refuses or fails to comply with a requirement of a designated medical practitioner in relation to the taking under that subsection of a specimen of blood or the provision under that subsection of a specimen of urine,

is guilty of an offence.

(5) In a prosecution for an offence under this Chapter it shall be presumed, until the contrary is shown, that an apparatus provided by a member of the Garda Síochána for the purpose of enabling a person to provide 2 specimens of breath pursuant to this section is an apparatus for determining the concentration of alcohol in the breath.