Calling a Witness Not Listed in a Witness List
Generally speaking, the purpose of a witness list is to provide notice of which witnesses will be called in order to prevent ambush at trial and to allow the trial to proceed in an orderly way and on time. However, occasionally, parties will seek to call a witness at trial that was not listed in their witness list. In personal injury actions, it is most often the defence that seeks to call such a witness, as defence work entails a lot of investigation, which may reveal potential witnesses. This investigation may be ongoing after the Trial Management Conference (and, therefore, after the Trial Briefs are served) or even after any amended witness lists are served. Because of this, certain defence witnesses may be unknown until just before or even at trial. Below is a discussion of when these witnesses may be called and points to bear in mind when seeking to call or oppose such late-notice witnesses.
Rule 7-4 provides as follows:
(1) Unless the court otherwise orders, each party of record to an action must, within the time set out in the case plan order or, if none, on or before the earlier of the trial management conference and the date that is 28 days before the scheduled trial date, file and serve on every other party of record a list of the witnesses the party may call at trial, other than
(a) expert witnesses who are to provide evidence under Part 11, and
(b) adverse witnesses referred to in Rule 12-5 (20) (a) or (b).
Requirements for list
(2) Unless the court otherwise orders, a witness list must include the full name and address of each listed witness.
(3) If a party who has provided a witness list or an amended witness list later learns that the list is inaccurate or incomplete, the party must promptly
(a) amend the witness list,
(b) file the amended witness list, and
(c) serve a copy of the filed amended witness list on all parties of record.
[am. B.C. Reg. 119/2010, Sch. A, s. 16.]
Witness need not be called
(4) Nothing in this rule requires a party to call as a witness at trial an individual named as a witness on a witness list served by the party under subrule (1) or (3).
Pursuant to Rule 12-5(28), a court has residual discretion to permit a party to lead evidence from a witness who is not listed on a witness list (Gichuru v Smith,  BCSC 1818 at para 34). This rule states,
Witness must be listed in witness list
(28) Unless the court otherwise orders, a party must not, at trial, lead evidence from a witness unless that witness is listed in a witness list.
Two of the main objects of witness lists and trial briefs are to ensure that the trial can proceed in an orderly way and on time, and that parties are not ambushed at trial by surprise witnesses (Gichuru v Smith,  BCSC 1818 at para 34).
Calling a witness not listed in a witness list
In an unreported decision made in Tompkins v Bruce,  BCSC 833 the Defendant attempted to call an unlisted witness at trial. Curtis J. refused to allow the witness to testify, providing the following reasons:
 …The new Rules say that you must give a list of your witnesses no later than 28 days before the trial, or the Trial Management Conference. There is a Trial Management Brief, which happened to be late filed; that is not a big deal, a late filing, but it just adds to the approach, I guess. Although the defendant knew that Mr. Simm existed, the Trial Management Brief says “lay witness number one” and “lay witness number two”. This not only does not conform with the Rules, but if permitted would deliberately frustrate them.
 The purpose of knowing who the witnesses are is so that the other side can prepare their case, and the Judge, if they want, can order a statement concerning the witnesses, as well as estimate the proper length of trial.
 At the Trial Management Conference, September 30th, a direction was given that the witness list will be provided at a subsequent date. The name of the witness was not provided until after that date. The explanation is that the address for the witness was not discovered until later.
 In the circumstances of this case, I am not prepared to allow Mr. Simm to testify, because one, I do not think his evidence is going to be particularly relevant in the circumstances of the case; two, his name was not disclosed, although it was known at the Trial Management Conference; and three, his name was not disclosed, although known, on the date that the Trial Management Conference Judge had directed that his name be given.
There are several points made by Curtis J. in the Tompkins decision that parties can rely upon in order to successfully argue that a witness should be called at trial even if he/she was not listed in their trial brief.
First, Curtis J. noted that simply stating “lay witness #” in a trial management brief not only does not conform to the Rules but would frustrate them. Thus, the party opposing the calling of the unlisted witness cannot argue that it would have been preferable if the other party wrote “lay witness #” rather than nothing at all.
Second, if the purpose of knowing who the witnesses are is to allow for the other side to prepare its case (i.e. to prevent ambushing at trial) this concern is not relevant when parties seeking to call the witness themselves did not know that the witnesses existed until very late, perhaps just before or at trial. Parties are not able to prepare themselves without knowing who they are. On the other hand, in Tompkins, Curtis J. stated that a reason for denying the opportunity to call the witness was because his name was not disclosed although it was known at the Trial Management Conference.
Third, unlike the intended witness in Tompkins, witnesses not listed in a trial brief may indeed be relevant in the circumstances of a case.
Fourth, unlike in Tompkins, the judge at the trial management conference may not direct that the witness’ name be given at a future date. This would likely occur in circumstances where a witness was not known to exist.
Calling a Witness listed in the opposing party’s witness list
In Lam v Chiu,  BCSC 441 the Plaintiff intended to call the individual Defendant, Ms. Chiu as a witness as part of the Plaintiff’s case and cross-examine her as an adverse witness pursuant to Rule 12-5(26). She was not listed in the Plaintiff’s trial brief. It was not a surprise that she would testify and she was listed in the Defendant’s trial brief, but it was a surprise that the Plaintiff intended to call her as a witness, rather than simply cross-examine her. The Defendant objected, arguing that it was both unfair and unnecessary – unnecessary because Ms. Chiu would be called in the Defence case and unfair because there was no indication to Defence counsel about this until the moment that Plaintiff’s counsel sought to call Ms. Chiu as a witness.
The court found that allowing the Plaintiff to call Ms. Chiu was not “abusive or clearly unjust”. Regarding the effect of the timing of the Defence learning that the Plaintiff intended to proceed this way, the court referred to Rule 12-5(28). The court noted that Rule 12-5(28) refers to witnesses being listed in a witness list, and does not say “has to be listed in the witness list as a witness to be called by the party which seeks to call that witness’ evidence” (para 28). Further, because the Rules allow for parties to call anyone as a witness at a trial with very limited discretion in the court to prohibit this, the effect of the timing of the advice was not sufficient to disentitle the Plaintiff from calling Ms. Chiu.