Section 4 of the Act of 1984 is amended -

(a) in subsection (1), by the substitution of "under or by virtue of any enactment or the common law" for "under or by virtue of any enactment",

(b) by the substitution of the following subsection for subsection (2):

"(2)

(a) Where a member of the Garda Síochána arrests without warrant, whether in a Garda Síochána station or elsewhere, a person whom he or she, with reasonable cause, suspects of having committed an offence to which this section applies, the person -

(i) if not already in a Garda Síochána station, may be taken to and detained in a Garda Síochána station, or

(ii) if he or she is arrested in a Garda Síochána station, may be detained in the station,

for such period as is authorised by this section if the member of the Garda Síochána in charge of the station to which the person is taken on arrest or in which he or she is arrested has at the time of the person's arrival at the station or his or her arrest in the station, as may be appropriate, reasonable grounds for believing that his or her detention is necessary for the proper investigation of the offence.