Should you list a witness statement that, later on, you may use at trial to impeach a witness? Yes.
 Counsel submits, first, that a prior inconsistent statement is not a document that could be used to prove or disprove a material fact. It is a document relevant only to credibility. Therefore, it is not required to be listed. Secondly, counsel submits that until the contradictory evidence was given by the witness, counsel had no intention of using the document at trial. The use of the document has only become necessary because of the surprise in the evidence that was given.Mr. Justice Harris disagreed, however, finding that such a document was prima facie relevant:
 I turn to deal with this point. I must say that I am sceptical that the plaintiff's argument is correct. It is common ground that the document here is covered by litigation privilege, which necessarily ties it into relevant issues in the litigation. Rule 7‑1(6) governs the listing of privileged documents. It is not obvious to me from the wording of the rule that the scope of the obligation set out in Rule 7‑1(6) is qualified or limited by Rule 7‑1(1).
 More importantly, however, prior inconsistent statements can be used, in my view, to prove or disprove material facts. Depending on how a witness responds to the statement when put to the witness, the effect of the use of the statement may well go beyond merely affecting credibility. The witness may adopt the content of the statement insofar as it relates to material facts; in that sense, at least, statements can facilitate the proof of material facts. Statements can facilitate the proof of material facts even if the witness does not adopt them, because findings on material facts may be affected by findings on credibility. But if a witness does adopt a prior inconsistent statement and accept the truth of it, that statement may be used as proof of the truth of its contents, and thereby be used to prove or disprove material facts.I am unsure about the first part of the analysis, at para. 14: "relevant [to] issues" is a standard of Peruvian Guano, which may be applicable to listing of documents under R. 7-1(11) - "relate to any or all matters in question in the action", but not R. 7-1(1), which only talks about documents that "could ... be used to prove or disprove a material fact."
The second part, at para. 15, however, seems to be directly on point. If a statement deals with a fact that you know to be a material fact in the action, than it is a statement that falls under R. 7-1(1) and should be listed as privileged. Moreover, there seems to be little downside to doing so. As it is privileged, there is little chance that the other side will obtain it from you, and by listing it, you will not be exposed to an argument that you can't use it at trial, as happened in this case.