Yes. In an Arizona personal injury case, a defendant may argue that someone who was never originally named in the lawsuit caused some or all of the injury, but Arizona law requires specific procedures before fault can generally be allocated to that nonparty.
This is known as identifying a nonparty at fault. When it occurs, the issue can significantly affect how responsibility and compensation are ultimately divided.
What Is a Nonparty at Fault in Arizona?
A nonparty at fault is a person or entity that allegedly contributed to an injury but is not currently a defendant in the lawsuit.
Arizona Revised Statutes § 12-2506 generally requires the factfinder to consider the fault of everyone who contributed to an injury, whether or not that person could have been named as a party. A defendant who wants fault assigned to a nonparty generally must provide the notice required by Arizona court rules.
For example, imagine that an injured driver sues another motorist after a collision. During the case, that motorist argues that a road contractor created an unsafe construction condition that contributed to the crash.
The contractor was not originally sued, but its potential fault may still become an issue.
As a Personal Injury Attorney, we look carefully for these issues because allocating fault to another person can reduce the percentage of responsibility assigned to a named defendant.
How Does a Defendant Identify a Third Party as Being at Fault?
A defendant cannot necessarily wait until trial and suddenly blame someone else.
Arizona Rule of Civil Procedure 26(b)(5) generally requires a party alleging that a nonparty was wholly or partially responsible to serve a notice identifying that nonparty no later than 150 days after filing its answer. The notice must provide the person’s identity and location, along with facts supporting the allegation.
The rule also requires timely supplementation when the notice becomes materially incomplete or incorrect.
If proper disclosure is not made, fault generally cannot be allocated to that nonparty unless the parties agree or the court permits it after considering good cause, reasonable diligence, and unfair prejudice.
For injured claimants, that means a nonparty-at-fault notice deserves careful attention rather than being treated as routine paperwork.
Why Would a Defendant Blame Someone Who Is Not in the Lawsuit?
The most direct reason is that Arizona generally follows several liability.
Under A.R.S. § 12-2506, each defendant is ordinarily responsible only for the portion of damages corresponding to that defendant’s percentage of fault, subject to statutory exceptions.
Suppose total damages are determined to be $200,000. If a named defendant is found 60% responsible and a nonparty is assigned 40% of the fault, the named defendant ordinarily would not be responsible for the nonparty’s entire share.
That creates an incentive for defendants to identify every other person or company that may have contributed to the injury.
Lawyers handling personal lawsuits therefore need to evaluate not only the defendant’s conduct but also whether the defense may attempt to shift responsibility elsewhere.
Does Naming a Nonparty Make That Person Legally Responsible for Paying Damages?
Not by itself.
Arizona law specifically provides that assigning a percentage of fault to a nonparty is used to determine the fault of the named parties. The allocation itself does not make the nonparty liable in that lawsuit or establish liability against that person in another action.
This distinction is important.
A jury could potentially assign substantial fault to someone who is not a defendant, reducing the portion attributable to the defendants who are actually in the case. But that does not automatically create a judgment against the absent person.
This is one reason identifying all potentially responsible parties early can matter in an injury claim.
Can the Injured Person Add the Third Party to the Lawsuit?
Potentially, depending on the facts and applicable deadlines.
When a defendant identifies another potentially responsible party, we may investigate whether there is evidence supporting a direct claim against that person or business. That can require reviewing contracts, incident reports, employment relationships, maintenance records, video, electronic information, or other evidence.
However, learning about another party does not automatically extend the applicable statute of limitations.
Waiting too long to investigate possible defendants can therefore affect which claims remain available.
A personal injury lawyer can evaluate potential responsibility early so that important parties are not overlooked.
What Types of Cases Commonly Involve Multiple Responsible Parties?
Third-party fault can arise in many types of personal injury matters.
Examples include:
- A vehicle collision involving several drivers
- A commercial crash involving a driver and employer
- An unsafe-property case involving an owner and maintenance contractor
- A construction injury involving several companies
- An accident involving defective equipment
- A collision involving unsafe road conditions
- An incident involving a driver performing work for another business
A Personal Injury Claim Lawyer may need to determine how the actions of several individuals or businesses combined to cause one injury.
This can make evidence about timing, control, contracts, and each party’s conduct especially important.
How Can Third-Party Fault Affect Settlement Negotiations?
A nonparty-at-fault argument can change how an insurer values a claim.
The defendant’s insurer may argue that its insured should bear only a small percentage of responsibility because another person, company, or even the injured claimant contributed to what happened.
That may lead to disputes about:
- Who controlled the dangerous condition
- Who had an obligation to prevent the harm
- Whether the third party actually contributed to the injury
- How much fault should be assigned to each participant
- Whether the evidence supports the defendant’s allegations
We evaluate these arguments against the complete factual record rather than assuming a defendant’s proposed allocation is accurate.
Why Does Identifying Every Responsible Party Matter in Arizona?
Arizona recorded 118,052 motor vehicle crashes in 2025, according to the Arizona Department of Transportation’s latest statewide data. ADOT also reported 1,156 traffic fatalities, marking the third consecutive annual decline while noting that roadway deaths remain near historically high levels.
Many personal injury cases are more complicated than a simple dispute between two people. Multi-vehicle collisions, commercial activity, property conditions, and contractor relationships can create several potential sources of fault.
Although motor vehicle claims are only one category of injury case, the volume of Arizona crashes illustrates why careful liability investigation remains important.
What Should You Do If a Defendant Blames Someone Else?
Do not assume that a defendant’s allegation establishes the third party’s fault.
A proper investigation may involve determining:
- What evidence supports the allegation
- Whether the defendant provided timely notice
- Whether the third party actually owed a legal duty
- Whether their conduct contributed to the injury
- Whether they should be added as a defendant
- Whether additional insurance coverage may exist
At Folger Law Firm, we examine these issues as part of building a complete picture of responsibility. As personal injury accident lawyers, our role is not simply to respond to the defense’s version of events but to investigate who actually contributed to the harm and what evidence supports each allocation of fault.
If another party is being blamed for your injuries, or you are unsure whether everyone responsible has been identified, call us at (602) 774-0033 or contact Folger Law Firm to discuss your Arizona personal injury claim.