Arrest without warrant: police may detain persons meeting prescribed suspicion, necessity, or public safety conditions lawfully. Police may arrest without a Magistrate's warrant where a cognizable offence is committed in the officer's presence or where reasonable complaint, credible information, or reasonable suspicion exists and the officer believes the offence occurred and considers arrest necessary to prevent further offences, secure investigation, preserve or prevent tampering with evidence, prevent inducement or threats to witnesses, or ensure court attendance; the officer must record reasons in writing, and where arrest is not required must issue a notice to appear, with compliance generally precluding arrest unless reasons to the contrary are recorded.