State v. Mahoney, No. 1 CA-SA 19-0067 (App. Div. I, May 16, 2019) (J. Johnsen) https://www.azcourts.gov/Portals/0/OpinionFiles/Div1/2019/1%20CA-SA%2019-0067.pdf

DEFENDANT MAY DESIGNATE UNKNOWN AND UNIDENTIFIED PERSONS AS NONPARTIES AT FAULT

Plaintiffs' decedent died when he hit horses who wandered onto State Route 77 near Dudleyville, Arizona. Plaintiffs  sued the horse owners, the owners of the Ranch where the horses were fenced and the State for allowing the horses to escape onto the highway through open gates. The defendants filed Nonparty at Fault designations of “unknown persons” and “Unknown ATV Riders” claiming they were the culprits who had left the gates opened ignoring a “KEEP GATE CLOSED” sign based solely upon the fact that ATV tire tracks were found in the area and the Sheriff's report concluded it must have been those riders who left the gate open. This was an area where it was known hunters and recreationists accessed public property frequently through these gates. Plaintiffs objected to these designations and the trial court struck them. The State brought this Special Action. The Arizona Court of Appeals accepted jurisdiction and granted the requested relief.

 "In assessing percentages of fault the trier of  fact shall consider the fault of all persons who contributed to the alleged injury, death or damage to property, regardless of whether the person was, or could have been, named as a party to the suit." A.R.S. § 12-2506(B).  Arizona Rule of Civil Procedure 26(b)(5) requires parties file a Notice of Nonparty at Fault disclosing “the identity and location of the nonparty allegedly at fault, and the facts supporting the allegation of fault.”

 In Rosner v. Denim & Diamonds, Inc., 188 Ariz. 431 (App. 1996) the court of appeals held the designation of unknown brawlers as nonparties at fault who injured the plaintiff in a fight at the defendant's bar was acceptable. The court held “like any procedural rule, Rule 26(b)(5) can only affect procedural matters and cannot abridge, enlarge, or modify substantive rights created by statute. Under § 12-2506(A), we explained, the issue is whether the defendant's notice discloses ‘facts sufficient to establish the existence of another tortfeasor, despite the inability to further identify the tortfeasor.'  .  .  .  At its heart, Rule 26(b)(5) is in service of a defendant's substantive right to have the jury assess fault to a nonparty – regardless of whether the plaintiff may hail that nonparty into court."