Jessiah MacDonald had a gun. His date of birth was January 24. He was a "non-white" male, around 6'2 (he was actually 6'4). He had a tattoo of a spider on his hand. He was a drug dealer. He had previously been in possession of a loaded firearm. He went by the nickname "Morrison". He had been recently driving a rental car and he lived with his surety. 
These details were given by an anonymous tipster who called the police to report that Jessiah MacDonald had a gun at his house. They were all confirmed - including the presence of the gun. This latter detail was confirmed when the police executed a search warrant at around 3 am.
MacDonald appealed the trial judge's dismissal of his Charter motion to exclude the firearm on the basis of an illegal searh. He appealed: 2012 ONCA 244.
On appeal the court began with the requirements for a search warrant. The court noted that the "material in support of the warrant must raise a reasonable possiblity of discovering evidence of a crime" [para 6]. Moreover the court noted that where the application is based on a CI the court must ask the following: