Applying for Judicial Authorizations
A warrant is a judicial order by a Judge or Justice of the Peace under statute authorizing a named person to enter into a location and seize specified evidence that is relevant to an offence.
The warrant has the effect permitting intrusion of a person's reasonable expectations of privacy. This is not dependent on ownership.
A search warrant is an "staple" investigative tool that assist police officers in determining the nature of a criminal offence and the identity of the culprit.
Source of Authority
A justice of the peace has no common law authority to issue a warrant, he may only issue warrants as provided by statute.
- Nova Scotia v MacIntyre,  1 SCR 175, 1982 CanLII 14 at p. 179 [SCR] ("an order issued by a Justice under statutory powers, authorizing a named person to enter a specified place to search for and seize specified property which will afford evidence of the actual or intended commission of a crime")
- R v Pugliese, 1992 CanLII 2781, (1992), 71 CCC 295 (Ont. CA) - building owner unable to assert privacy rights over apartment
- R v Cunsolo, R v Cunsolo, 2008 CanLII 48640 (ON SC),  O.J. No. 3754 at para 135
- See Hutchison, The Law of Search and Seizure s. 16(b) citing R v Paint (1917) 28 CCC 171 (NSCA)(*no link) ("At common law the dwelling of the subject is held to be immune from intrusion, unless there is express authority to justify the intrusion, and the 'person" of the subject is held equally sacred.")
- R v Sadikov, 2014 ONCA 72 (CanLII), 305 CCC (3d) 421, at para 83
- R v Campbell, 2011 SCC 32 (CanLII),  2 SCR 549, at para 14
Types of Warrants
The Criminal Code provides for several types of search warrants:
There are other search and seizure powers found under a variety of other federal Acts that are not directly criminal in nature. Most notable include:
- Income Tax Act,
- Excise Act,
- Competition Act (s. 16),
- Canadian Environmental Protection Act (s. 220),
- Antarctic Environmental Protection Act (s. 32),
- Hazardous Products Act (s. 22),
- Bankruptcy and Insolvency Act, and
- Fisheries Act
Purpose of a Warrant
A search warrant makes valid act which would otherwise be considered trespass.
The purpose of a search warrant is to allow investigators to "locate, examine and preserve all the evidence relevant to events which may have given rise to criminal liability."
A search warrant can be used not only for collecting evidence supporting a criminal charge but also as an investigative tool for alleged criminal activity.
The items sought need not necessarily afford evidence of the actual commission of the offence under investigation. Rather it "must be something either taken by itself or in relation to other things, that could be reasonably believed to be evidence of the commission of the crime." 
- R v Pugliese, 1992 CanLII 2781 (ON CA) ("entry upon private lands by officials of the state was a trespass unless there was a lawful authorization for the entry.")
- R v Vu, 2011 BCCA 536 (CanLII) at para 30 citing CanadianOxy Chemicals Ltd. v Canada (Attorney General), 1999 CanLII 680 (SCC),  1 SCR 743 at 20-22
- Descôteaux v Mierzwinski, 1982 CanLII 22 (SCC),  1 SCR 860 at 891
R v Vu 2011 BCCA 536 (CanLII) at para 29
- R v Vu at para 31 citing R v Canadian Broadcasting Corp., (1992), 77 CCC (3d) 341 at 351 (Ont. Ct. (G.D.))(*no link)
Procedure for Obtaining a Warrant
An application for a search warrant consists of a request under the enabling provision along with evidence, usually in written form, supporting the application. This evidence usually takes the form of an "Information to Obtain" (ITO) with a draft warrant. Both are then presented to a justice of the peace or judge. An ITO consists of a statement under oath or an affidavit of an informant detailing the facts known (both first hand or second hand) that would provide basis to issue a warrant.
An application for a warrant is an ex parte motion and as such must "make full, fair and frank disclosure of all material facts".
A justice of the peace must act judicially in issuing warrants. This requires that they maintain their independence. They may not take part in the drafting process by reviewing incomplete application and give advice on them.
A warrant that was signed before the ITO was sworn does not invalidate it. It is the "issuance" of the warrant, not the signing, that requires that it be supported by a sworn ITO.
A judge or justice of the peace rejecting a search warrant application can provide the applicant with a list of errors or omissions that make the warrant deficient without losing their responsibility as a neutral arbiter.
A judge or justice may indicate to the police seeking authorization that the process is believed to be wrong and brought under a different section. They may also advise on what further information may be needed and point out deficiencies. 
Appealing a Rejected Warrant
There is not normally a right of appeal for a rejected search warrant. However, an application of certiorari or mandamus may be available.
Since there is no right of appeal, there is no prohibition against re-applying to the same or another judge or justice for the warrant with the same materials.
- R v Truong, 2012 ABQB 182 (CanLII)
R v Krist, 1998 CanLII 6105 (BC CA), at para 8
R v Gray, 1993 CanLII 3369 (MB CA), ("It is of course open to a magistrate hearing an application for a warrant and considering the evidence presented to identify deficiencies and to reconsider the application when these deficiencies have been remedied by the police")
R v Duchcherer and R v Oakes, 2006 BCCA 171 (CanLII), at para 33