“(3A) A member of the Garda Síochána may arrest without warrant a person who in the member’s opinion is committing or has committed an offence under subsection (3) of this section where the contravention involves or, as may be appropriate, involved non-compliance with paragraph (a) or (b) of subsection (1) of this section, injury was caused to person, a mechanically propelled vehicle was involved in the occurrence of the injury and the first-mentioned person is, or as may be appropriate, was in the member’s opinion the driver of the vehicle concerned.”.