In the recent decision of Bowles v. Hillson, the Ontario Superior Court again considered when it is appropriate to extend the two-year limitation period for adding a defendant to a claim. The Court also commented on the issue of "due diligence" in ascertaining the identity of a potential defendant and how that may be demonstrated.

The plaintiff commenced an action against a surgeon and other defendants after a piece of the surgical equipment used by the defendant surgeon broke off and became lodged in the plaintiff's iris during cataract surgery. The plaintiff was not advised of the identity of the equipment's manufacturer, AMO, until almost three years following the date of loss and a year after commencing the claim, well outside the two-year limitation period. The plaintiff claimed he acted with diligence in attempting to ascertain AMO's identity, including making inquiries of the defendant surgeon. It was not until his lawyer received a letter from counsel for the surgeon three years following the date of surgery that he became aware of AMO's involvement. The proposed defendant AMO alleged the plaintiff failed to take reasonable steps to identify AMO and failed to ask the defendant surgeon the "right question," i.e., who manufactured the tool in question.

The Court concluded that the plaintiff ought to be permitted to add AMO as a defendant. The evidentiary threshold to amend the claim on the basis of discoverability was, "not high so long as the plaintiff puts in evidence of the steps taken to ascertain the identity of the tortfeasor and gives a reasonable explanation on proper evidence as to why such information was not obtainable with due diligence." The Court relied on the fact that the plaintiff had made multiple inquiries of the defendant surgeon about the manufacturer, and had requested to see the tool in question to determine who manufactured it. The surgeon responded that he did not know where the tools were or which particular tools were used. The evidence showed that the surgeon had been in contact with AMO about the tools in question, but he did not disclose this to the plaintiff and instead opted to deal with the matter himself, believing it to be "offside" to disclose the manufacturer's identity. Further, none of the records produced by the defendants identified AMO as the manufacturer of the instrument. In finding for the plaintiff, the Court held that to demonstrate a reasonable investigation had been made, the plaintiff need not conduct "a pre-discovery discovery of an adverse party" and did not accept that the plaintiff failed to ask the "right question."

Bowles provides an example of what type of investigation may be accepted by a Court to show that "due diligence" has been exercised in attempting to identify a potential defendant. In this case, the named defendant's failure to disclose the identity of a potential co-defendant, despite inquiries from the plaintiff, demonstrated due diligence and therefore the plaintiff met the relatively "modest" evidentiary burden to amend the Statement of Claim.