Is there any case law supporting the assertion of privileged information?

In Pearson v. Inco Ltd., Cullity J. referred, at para. 15, to the following statement of law by Professor Robert J. Sharpe in "Claiming Privilege in the Discovery Process" in Law in Transition: Evidence, [1984] Special Lect. L.S.U.C. 163, at p. 169: It is well established in the case law that where a party on discovery has asked for facts relating either to his own case or to that of his opponent, those facts must be revealed, not withstanding that the party's source of information is a privileged report or document.