In the absence of an arrest warrant, a police officer (or private citizen) may arrest you if you are found committing an offence. Alternatively, a police officer may arrest you if he/she has “reasonable and probable grounds” to believe that you have or are about to commit an indictable offence. What this means in court is that there must have been a “credibly based probability” that you either committed or were about to commit an indictable offence. Otherwise, the Court may deem the arrest unlawful and you may be entitled to constitutional relief. Following an arrest, the decision to lay criminal charges depends on the discretion of the police as well as the evidence they have gathered. Evidence can be either physical, documentary or testimonial.