If you have been arrested under a criminal offence, the police have the option to release you without a bail hearing. Your release will be contingent on a promise to appear to a court date, and in most cases, to appear for fingerprinting. You may also be released on an undertaking, which is a signed document stating the conditions of your release.
Whether or not the police are opposed to your release, they must arrange a bail hearing within 24 hours of the arrest before a Justice of the Peace or a Provincial Court Judge. You are entitled to counsel for a bail hearing and your lawyer will always take steps to negotiate terms of your release with a bail prosecutor where possible.
Murder is an exception to this rule. Additionally, if the Crown Prosecutor consents to your release, then the court must grant bail.
Typically, the Crown bears the burden of proof to satisfy the court that the detention of the accused is necessary.
Certain offences like narcotics or drug charges have a reverse onus whereby the accused must justify their release to the court. An accused who has already been granted judicial interim release on a different charge is also subject to a reverse onus.