The doctrine of Present Memory Revived permits a testifying witness to jog their memory. The tool used to jog the memory can be anything (a sound, a picture, a smell, etc). It is not the aid that becomes the evidence but rather it is only a mechanism to evoke the memory of the witness which produces the evidence.
The procedure to refresh memory in the context of a prior recorded statement reduced to writing is as follows:
- on direct examination, counsel should put the statement in the hands of the witness
- counsel should direct the witnesses attention to the part which contains the previous answer
- the witness should read it to himself
- the counsel may put questions to the witness referring to the previous answer. The witness may correct an error, agree or deny the contents of the document
The fundamental principles were summarized in Cornerstone Co-operative Homes Inc. v Spilchuk,  O.J. No. 4094 at para 13:
- There is a distinction between present memory revived and past recollection recorded: in the former, something once remembered is again remembered by means of the memory being jogged by reference to, for example, a note; in the latter, "one has a record of what was once remembered but is no longer remembered . . . [I]t is only where a present memory is actually revived that it can be said to be 'refreshed'": see Mewett, Alan W., Witnesses (Toronto: Carswell, 1997 -- Rel. 2), pp. 13-2 and 13-3.
- The memory of a witness may be refreshed by any document. "[A]nd it makes no difference that the memorandum is not written by [the witness], for it is not the memorandum that is the evidence but the recollection of the witness": see Henry v. Lee (1814), 2 Chit. 124, approved in R. v. B. (K.G.) 1998 CanLII 7125 (ON CA), (1998), 125 C.C.C. (3d) 61,  O.J. No. 1859 (C.A.), at p. 67 C.C.C.
- In a case where a witness refreshes his or her memory "from some external source or event, she has a present memory, albeit one that has been refreshed; how reliable and truthful her recollection is, will be determined by the trier of fact . . .": see R. v. B. (K.G.), ibid.
- There is no need for the note or document used to refresh memory to have been made contemporaneously with the facts in the note or document: see R. v. B. (K.G.), supra, at p. 69 C.C.C.
- There is nothing wrong with a witness reviewing a written statement made by her years earlier for the purposes of refreshing her memory before trial and there is nothing wrong with cross-examining counsel attempting to determine whether the witness "had a present memory of events about which she testified": see R. v. B. (K.G.), supra, at p. 67 C.C.C.
- The statement in R. v. Kerenko, Cohen and Stewart,  3 C.C.C. 52, 49 D.L.R. (2d) 760 (Man. C.A.), at p. 53 C.C.C., that "it is only where the witness requires his notes to refresh his memory at trial that he may be called upon to produce them" (emphasis added) would not seem to be good law, at least in Ontario.
- It would also seem to be true that it does not make any difference how long before trial the refreshing occurs. Cross-examining counsel is entitled to explore this and other matters to ascertain the reliability and truthfulness of the witness.
The document cannot be put to the jury or in any way be put into evidence.
The court must be cautious when a witness is using documents to refresh their memory. Where the witness is relying too much on the notes for their testimony there is a likelihood that they are not testifying to their memory and are simply reciting their notes.
While as a general rule the document being used to revive the memory should be disclosed to the other side, this is not necessary in the case of a statement generated by the accused. So a statement made by the defence that is protected by solicitor-client privilege is not disclosable to the crown. If however the statement was purely created as a aide memoire then it may not be privileged. It is normally desireable for defence to make the purpose of the document clear on the document itself.
The privilege further remains in place even at the time that it is used in court to refresh a memory.
Defence witness statements by non-accused persons are not generally protected by solicitor-client privilege.
There is nothing necessarily wrong with officers reading the statements of other witnesses as long as no coaching is involved.
Where officers collaborate on their notes that they refer to decreases the likelihood that the officer is actually refreshing their memory. This will inevitably go to the officer's credibility.
Generally speaking, statements should not be read in the presence of the any other witness.
Present memory revived is separate and distinct from Past Recollection Recorded which is a form of hearsay. In the later case, the document is evidence that the judge may rely upon.
See also: R. v. Violette, 2009 BCSC 503 
- eg. R. v. K.G.B. (1998), 109 O.A.C. 138, 125 C.C.C. (3d) 61 at 18 
- R. v. Rowe, 2008 NLCA 3
- See also R. v. Gadzo, 2009 ONCJ 126
- e.g. R. v. Mattis  O.J. No 4332 (Ont. Prov. Ct.)
- R v Fast  BCJ No 2421 (BCSC) at para. 29-31
- R v Parker  OJ No 175 (CA)
- R v Husbands (1973) 24 CRNS 188
- R v Mattis, supra
R v Green  O.J. No. 3598 (Ont. Gen. Div.) at para. 24
- R v Husbands (1973) 24 CRNS 188
Using a Prior Transcript to Refresh Memory (Coffin Application)Edit
Where a witness forgets or does not remember certain information that has been previously recorded under oath or in a written statement, counsel may show a copy of the previous statement to refresh the witness's memory.
In such circumstances where the questioning on a prior statement is not for the purpose of discrediting or contracting the witness, which would engage s. 9 of the Canada Evidence Act, "the court has a discretion... to relax [the rule when] it is considered necessary in the interest of justice."
- R v Coffin  S.C.R. 191 at pp. 22-23