15. (1) Upon receiving any such complaint or information, the justice of the peace shall hear and consider the allegations of the complainant, and, if the justice consider it desirable or necessary, the evidence of any witness or witnesses; and, if the justice be of opinion that a case for so doing is made out, he shall issue a summons, or warrant, as the case may be, in the manner hereinafter provided.
(2) The justice of the peace shall, in connection with such hearing, have the same power of procuring the attendance of witnesses and of compelling them to testify as that with respect to the summoning and appearance of witnesses at the trial.
(3) The evidence of witnesses, if any, at such hearing, shall be given upon oath.
(4) Such justice of the peace shall not refuse to issue such summons or warrant only because the alleged offence is one for which an offender may be arrested without warrant.