based upon a warrant issued by a local magistrates' court or upon reasonable cause in the mind of the arresting officer. A warrant issued by a magistrates' court is issued in response to an application by a police officer, who swears an information in writing. The warrant is issued if the magistrate is satisfied that a summons to appear before a criminal court will be ineffective. Summons are usually considered to be ineffective in all but summary offenses, since a suspect accused of a serious offense is unlikely to voluntarily appear before a court to answer charges if he or she believes that conviction is likely.
The warrant issued by the court can be enforced after any length of delay and it may even be applied for at any time after the commission of the crime, since there usually is time limitation in proceedings for indictable offenses. At the time of arrest, the suspect need not immediately be shown the warrant, but must be informed that there is a warrant out for his or her arrest and be shown the warrant as soon as is practicable. Once a warrant is issued, it can only be withdrawn with leave of the magistrate who issued it.
A police officer need not apply to a magistrates' court for a warrant if he or she has reasonable cause to believe that the suspect has committed an "arrestable offense." Such an offense is one which is punishable by up to five years in prison for a first-time offender. Evidence which is sufficient to constitute reasonable cause may not be sufficient to justify charging the suspect for the crime. Reasonable cause can take into account items which might not be admissible at trial or which, while admissible, would not prove the case standing alone. The reasonable cause standard is that a reasonable man, acting without passion or prejudice, would fairly have suspected the person arrested of having committed the offense. In contrast, in order to charge the individual arrested with the crime...