If there are concerns that witnesses at trial will try to ‘match-up‘ their testimony it is important to exclude them from Court before they testify. In British Columbia the Supreme Court Rules don’t have any provision addressing the exclusion of witnesses during trial, however the Court retains a discretion to make such an order pursuant to it’s ‘inherent jurisdiction‘. Reasons for judgement were released today providing a summary of this area of law.
In today’s case (He v. Yeung) the parties had a dispute about a commercial relationship. The key witnesses to the negotiations were expected to testify and the Court was asked to decide whether an order should be made excluding these witnesses before they took the stand. Mr. justice Burnyeat refused to make such an order and in doing so provided the following useful summary of this area of BC Civil Procedure:
 McLachlin and Taylor, British Columbia Practice (3rd ed.), Looseleaf (Markham, Ont.: LexisNexis Butterworths, 2006), sets out this statement regarding the practice in British Columbia:
One limitation on the principle of an open court is the practice as to exclusion of witnesses. The court, upon application of any party, may order that witnesses be excluded in the interest of securing the best possible evidence. While the British Columbia Rules, unlike those of certain other jurisdictions, do not expressly confer a power to exclude witnesses on the court, it appears that the court has an inherent power to make such an order: see Moore v. Lambeth County Court Registrar,  1 All E.R. 782 (C.A.). The practice is for counsel to ask for an order excluding witnesses. …. If a witness defies an order of exclusion or circumvents it by discussing the proceedings with those who were present in the courtroom, his evidence cannot be excluded for this reason, although the weight given it may be reduced: Crawford et at. v. Ferris,  O.W.N. 713 (H.C.); R. v. Dobberthien,  6 W.W.R. 539 (Alta. C.A.), affd (sub nom. Dobberthien v. The Queen) (1974), 50 D.L.R. (3d) 305 (S.C.C.). Moreover, the witness may be cited for contempt:R. v. Carefoot,  2 D.L.R. 22 (Ont. H.C.).
(at p. 40?2)
 The Learned Author of The Law of Evidence, 10th ed. (London: Sweet & Maxwell, 1906) states:
If the judge deems it essential to discovering the truth that the witnesses should be examined out of the hearing of each other, he will order them all on both sides to withdraw, excepting the one under examination. Such an order is, upon the application of either party at any period of the trial, rarely withheld, but it cannot be demanded of strict right.
(footnotes omitted) (at pp. 1007-1008)
 A more extensive history tracing the practice as far back as the story of Susannah from the Book of Daniel is set out in Wigmore, A Treatise in the Anglo-American System of Evidence in Trial at Common Law, Vol. 6 (Boston: Little Brown, 1940). Wigmore states that the practice came from Germanic common law which the English law inherited.
 While the Rules of Court in Alberta (since 1923), in Manitoba (since 1913), in Ontario (since 1913), and in Saskatchewan (since 1921) provide that a judge may order a witness to be excluded at the request of either party, no such provision is specified in the British Columbia Rules or in a British Columbia statute. Accordingly, it is the inherent jurisdiction of the Court which confers the power to exclude witnesses in civil trials.
 The traditional reasons for excluding witnesses include: (a) if the hearing of opposing witnesses were permitted, the listening witnesses could ascertain the points of difference between their testimonies and could shape their own testimony to better advantage; and (b) regarding witnesses on the same side of the litigation, it deprives the later witness of the opportunity of shaping his or her testimony to correspond with the testimony of the earlier witness.
 In Bird et al. v. Vieth et al. (1899), 7 B.C.R. 31 (S.C.–F.C.), McColl C.J. on behalf of the Court stated that the ruling of a trial judge to exclude defendants as if they were witnesses was in error, and that a new trial should be allowed. In the context of that appeal, the following statement was made:
We are of opinion that the learned trial Judge erred in dealing with the question of the defendants’ exclusion from the Courtroom as if they were in the same position as a witness, not a party to the action, whose exclusion, if requested, is commonly ordered as of course. (at pp. 31?32)
 In McIntyre et al. v. McIntyre,  2 W.W.R. 581 (B.C.S.C.), Macdonald J. ruled that both plaintiffs who would be witnesses were entitled to remain in the Court but that, with the concurrence of their counsel, the one plaintiff would be excluded while the other plaintiff was giving evidence. The rationale for why it was necessary for the plaintiffs to be available was described as follows:
If that were granted and the plaintiff excluded, something might arise and counsel would not be aware of what his client’s views were on the matter, and he would have to run out of Court. … The party instructing counsel would not be in a position to conduct his case if he were excluded from the Court. (at p. 582).
 In the context of a criminal appeal, Branca J.A. made this statement in R. v. Smuk,  4 W.W.R. 613 (B.C.C.A.):
In my practice, in our law courts, counsel have always asked for an order excluding witnesses and the order is a discretionary one. On the civil side the litigants, of course, have an absolute right, subject to certain exceptions, to remain in court and on a criminal charge the accused has the same right.