R. v. Cleghorn,  3 S.C.R. 175
The appellant was convicted of trafficking in cocaine. An
undercover officer arrived at the scene of the transaction at 2:18 p.m. The halfminute transaction took place sometime thereafter and was completed not laterthan 2:25 p.m. The undercover officer identified the individual involved as the appellant, who was then arrested, at about 3:40 p.m. The appellant presented alibi evidence at trial that he was at home with his mother at the time of the alleged transaction. The trial judge considered this evidence to be significantly weakened because of want of formal disclosure of the alibi and noted that this finding may have had a significant effect on the outcome of the trial. A conversation which took place between the accused's mother and the police when she was arranging bail was considered to be inadequate disclosure of the alibi. The mother claimed during this conversation, which focused on
determining the time of the arrest, that the accused was with her at 2:30, 3:00
and 3:15 p.m. An appeal to the Court of Appeal was dismissed. The issues here were whether or not the disclosure of the alibi evidence was properly characterized as untimely or insufficient, and if so, whether or not the conviction could nevertheless be upheld pursuant to the provisions of s. 686(1)(b)(iii) of the Criminal Code.
Per Lamer C.J. and Gonthier and Iacobucci JJ.: Proper disclosure of an alibi has two components: adequacy and timeliness. The consequence of a failure to disclose an alibi properly is that the trier of fact may draw an adverse inference when weighing the alibi evidence heard at trial. Improper disclosure can only weaken alibi evidence; it cannot exclude it. The rule, which is one of expediency, is intended to guard against surprise alibis fabricated during testimony at trial. It has been adapted to conform to the Canadian Charter of Rights and Freedoms norms in that disclosure is proper when it allows the prosecution and police to investigate the alibi evidence before trial. The criteria of timeliness and adequacy are thus evaluated on the basis of whether a meaningful investigation could have been undertaken as a result of disclosure.
Neither disclosure at the earliest possible moment, nor disclosure by the
accused is necessary. Third party disclosure is sufficient.
The timeliness of the disclosure was not at issue. The statement to
the police by the accused's mother was unclear and confused and did not
disclose sufficient detail and coherence to enable the police to undertake a
meaningful investigation of the evidence supporting the alibi. The key factor to
be considered was the time of the commission of the offence in question. The
mother's statements to the police focused on the accused's whereabouts at the
time of his arrest. The claim that he was with her at 2:30, at 3:00 and at 3:15
(the times the officer recited to her), did not strictly relate to the time of the
commission of the offence, which was between 2:18 and 2:24. This fact
undermined further the suggestion that this conversation was sufficient to put
the police on notice as to the alibi. The assertion that the accused was not
present at the location of the crime, when it was committed, is missing from the
alibi. The trial judge was entitled to draw a negative inference based on the
evidence before him.
R. V .J.B.J., 2011 NSCA 16 (CANLII)
 To address this factor it is necessary to look at the law as it relates to alibi evidence.
 With respect, the trial judge appears to have misunderstood or, at the very least, failed to properly apply the law relating to alibi evidence. The appellant did not need to prove his alibi; the evidence of his alibi need only raise a reasonable doubt that he committed the crime: Lizotte v. The King, 1950 CanLII 48 (S.C.C.),  S.C.R. 115.
 Further, the alibi of an accused does not have to be corroborated by independent evidence in order to raise a defence (R. v. Letourneau ,  B.C.J. No. 265 (Q.L.)(C.A.), ¶ 61).
 Courts have long recognized, as well, that alibi evidence will frequently be given by relatives and friends of the accused. While this is a reality which may be considered, the evidence cannot be rejected on this ground alone: Cloutier v. R. (1960), 44 C.R. 60 (Que. C.A.) at ¶ 37:
 ... There is no evidence that any of these were particularly friendly with appellant. It is almost inherent in a defence of alibi that it must be made through witnesses acquainted with the accused, and I do not consider that the defence can properly be rejected on this ground alone.
 Finally, alibi evidence by its very nature is self-serving. The accused is saying he was not present at the time the crime was committed. What could be more self-serving?
 Thus, the trial judge erred by summarily rejecting the defence evidence on the grounds that it was self-serving and not corroborated by independent evidence.
 In R. v. Parrington reflex, (1985), 20 C.C.C. (3d) 184 (Ont. C.A.), Cory, J.A. (as he then was) offered helpful advice as to how alibi evidence should be considered by a trier of fact:
1. if they believe the alibi testimony given, then they must acquit;
2. if they did not believe such testimony, but were left in reasonable doubt by it, again they must acquit the accused;
3. even if they were not left in reasonable doubt by his testimony, then, on the basis of all the evidence, they must determine whether they are convinced beyond reasonable doubt of the guilt of the accused (¶ 7).