Plaintiff Tyman tripped and fell on a sidewalk in 2002. On the eve of the expiration of the statute of limitations, she filed a complaint naming various corporate entities, as well as 30 "John Doe" defendants. Further investigation resulted in Tyman filing an amended complaint, less than 2 months after the initial complaint, dropping all named defendants and adding three new ones, including Hintz Concrete. The amended complaint was served on the 3 new defendants roughly three months after the expiry of the limitations period. Tyman argued that the amended complaints "related back" under Rule 15(c). The Superior Court granted the new defendants' motion for summary judgment on limitations grounds, holding that there was no "mistake" as to the proper party sued; and the Court of Appeals affirmed, under different rationale.
The Supreme Court began by noting that the dispositive issue in this case was whether the new defendants "knew or should have known that, but for a mistake concerning the identity of the proper party, they would have been named in the original action." Slip Op. at Para. 12 (internal citation omitted). The Court held first that Rule 15(c)(2) provides for relation back when defendants knew or should have known of a mistake within the limitations period PLUS the period provided by Rule 4(i) for service of the summons and complaint. Slip. Op. at Para. 15. The Court further explained that during the relevant period, the potential new defendant must have knowledge of the mistake of identity, not of the occurrence that is the subject of the suit. Id. at Para. 16.
The Court then turned to what constitutes a "mistake" within the meaning of Rule 15. Relying principally on the 1st Circuit's decision in Leonard v. Parry, 219 F.3d 25, 28 (1st Cir. 2000), the Court held that the proper inquiry is "whether, in a counter-factual, error-free world, the action would have been brought against the proper party." Slip. Op. at Para. 19, quoting Leonard, 219 F.3d at 29. The critical information, explained the Court, is what the Plaintiff knew or thought he knew at the time of the original pleading. Id. And it is Plaintiff's burden to establish that the potential new defendant "truly was omitted because of a mistake concerning the identity of the proper party." Id. at Para. 22 (internal citation and quotation omitted).
Here, the Court held that Tyman had not carried her burden of demonstrating mistake. Instead, she simply did not know, at the time of the original complaint, who the proper parties were. Such circumstances do not constitute a mistake under Rule 15.
Lastly, the Court dismissed Tyman's argument that her counsel's "reasonable diligence" within the limitations period should allow her amended complaint to relate back. The Court noted that this argument conflates "relation back" with the "discovery" rule for tolling the limitations period under certain circumstances. See Slip. Op. at Para. 24, citing Walk v. Ring, 202 Ariz. 310, 315-16 (2002).
The Court affirmed the decision of the Superior Court and vacated the decision of the Court of Appeals. Justice Hurwitz authored the decision, in which the entire Court concurred.