Whenever in exercise of any power or the performance of any duty under this Act any member of the Gárda Síochána makes in a public place any request, requisition, or demand of any person, such person shall not be bound to comply with such request, requisition, or demand unless such member either -
(a) is in uniform, or
(b) produces, if requested by such person, an official identification card or such other evidence of his identity as may be prescribed.