Police will often rely upon confidential informers to form their grounds to affect a warrantless arrest or for the issuance of a judicial authorization such as a search warrant. These are most pervasively seen in dealings related to drugs and organized crime where confidential communications are so often shared to persons who may have an interest in revealing it to police officers.
Information from a confidential informer is only admissible where the defence challenges the grounds of a search, seizure, or arrest, otherwise it is not relevant.
A "tip" from an anonymous or confidential source can be used to form the grounds of arrest or search. The "tip" must be considered based on: 
- the degree of detail provided;
- the informant's source of information;
- the informant's prior reliability.
This test was previously stated as the "Debot" test requiring the three "C"s:
- was the information predicting the commission of a criminal offence "compelling"?
- where that information was based on a "tip" originating from a source outside the police, was that source "credible"?
- was the information "corroborated" by police investigation prior to making the decision to conduct the search?
All these factors are to be balanced together in the "totality of the circumstances" to determine if the evidence meets "the standard of reasonableness".
The test remains the same whether considering a warrantless search or a warrant such as a wire-tap.
Hearsay from the informant can be sufficient.
The law must maintain a "distinction between acting on a tip from a reliable source and acting on a tip from an unproven source". Where reliability is unknown, "a relatively thorough investigation is essential" in order to provide corroboration.
Consideration of the reliability of the information must be at the time of the warrantless search or application for a warrant. It cannot be considered ex post facto from the results of the search.
The purpose of considering the level of detail is to "ensure that it is based on more than mere rumour or gossip"
It is insufficient to rely on conclusory statements without any information on the "source or means of knowledge and whether there are any indicia of his or her reliability, such as the supplying of reliable information in the past or confirmation of part of his or her story by police surveillance"
Confirmation of the criminal aspects of a tip is important in cases such as where the tip is anonymous.
Where there is no corroboration or confirmation, the reliability of the source is the essential issue.
R v Graham, 2013 BCCA 75 (CanLII) at para 15
R v Jir, 2010 BCCA 497 (CanLII) at para 8
- R v Warford (2001), 161 CCC 309, 2001 NFCA 64 (CanLII)
R v Garofoli, 1990 CanLII 52 (SCC),  2 SCR 1421 at para 68
- R v Debot,  S.C.J. No. 118 1989 CanLII 13 at p. 218-219
- R v Debot
R v Garofoli at para 68, 82 to 83
Araujo at para 54
- R v Bennett (1996) 108 CCC 175, 1996 CanLII 6344 (QC CA)
R v Debot at p. 1168
R v Plant, 1993 CanLII 70 (SCC) at para 35
- R v Garofoli at para 68 ("I see no difference between evidence of reliability of an informant tendered to establish reasonable and probable grounds to justify a warrantless search ... and evidence of reliability of an informant tendered to establish similar grounds in respect of a wiretap authorization.")
- R v Garofoli at para 68
R v Philpott,  O.T.C. 990, 2002 CanLII 25164 at para 161
Philpott at para 162
- R v Garofoli at para 68
- R v Greffe, 1990 CanLII 143 (SCC),  1 SCR 755
see also R v Debot, 1986 CanLII 113, (1986), 30 CCC (3d) 207 (Ont. C.A.) per Martin JA at p.218 ("The underlying circumstances disclosed by the informer for his or her conclusion must be set out, thus enabling the justice to satisfy himself or herself that there are reasonable grounds for believing what is alleged. I am of the view that such a mere conclusory statement made by an informer to a police officer would not constitute reasonable grounds")
- see R v Campbell, 2003 MBCA 76 (CanLII) at par. 27
R v Maton, 2005 BCSC 330 (CanLII) at para 45
R v Pippin 1994 CanLII 4659 (SK CA)
R v Cheecham, 1989 CanLII 5129 (SK CA), (1989), 51 CCC (3d) 498 (Sask. C.A.)
R v Duther, 2002 NBPC 4(*no link)
R v Duncan 2004 MBCA 64 (CanLII)
Level of Detail
- Length of discussions with informer
- Amount of information known of accused (by name or description)?
- Did information include the location of criminal offence?
- did information include nature and quality of drugs?
- did information include the nature of the deal?
In a drug trafficking case, details that should often be considered include:
- type of drug observed, the amount of drug present, and how informer would have known;
- location within the residence in which the drug was observed or stored;
- observations regarding indicia of intent to offer for resale;
- recency of observations; and
- location of sources at time of observation, whether it was made inside or outside.
It is important that the corroboration relating to details of the offence not simply be neutral facts of a non-criminal nature.
There is nothing wrong with having two informers cross-corroborate each other in assessing whether sufficient grounds exist.
Where the level of detail is low and where credibility cannot be assessed, the obligation on corroboration increases.
Where the reliability of the source is unknown, corroboration is "particularly important". There must be sufficient corroboration "to remove the possibility of innocent coincidence".
Often evidence from surveillance or other investigative tools will corroborate the informer. 
Reliability and Credibility
- Past reliability:
- Length of time known
- Frequency of contact
- # of times paid (before / after incident)
- # of valid search warrants based on his information
- Had searches resulted in seizure of drugs/monies/weapons (If so, in what amount?)
- Had information resulted in convictions?
- # of negative, false or inaccurate information?
- # of cases resulted in dismissed/acquitted/withdrawn
- Credibility of Informer
- Did they have pending charges at the time?
- Non-conclusory information
- Did thye have a criminal record? For offences of dishonesty? If so, how many, and how long ago?
- Informers source of knowledge
- 1st, 2nd or 3rd hand information? (3rd degree is as good as anonymous)
- Freshness of the information
An informer with a criminal record is quite frequent and expected. The presence of a record should not necessarily negate the value of the information. However, offences such as perjury will likely have an impact on their credibility. 
There are a variety of motives to be an informant, including.
- Fear such as the threat of incarceration;
- Perverse motivation;
- Egotistical motivation;
- Mercenary motivation such as the receipt of money.
Disclosure of Handler Notes
Simply classifying materials as "handler notes" does not necessarily afford them the protection of informer privilege.
The burden is upon the accused to demonstrate "that there is a reasonable likelihood that the requested materials will assist the court in the determination of the application".
SHN are "first party disclosure, unless those reports concern only general information unrelated to a particular accused and investigation
"Sufficient reliability is established, or is not established, by reference to the material filed in support of an application for an authorization"
- Cases on Informers in Warrantless Searches
- Informer Privilege
- Information to Obtain a Search Warrant