Arizona's fault system: at-fault, not no-fault

Arizona runs on an at-fault system. Whoever caused the crash, and that driver's insurance, is responsible for the harm they did. There is no personal injury protection (PIP) requirement here and no no-fault law that routes you to your own insurer first regardless of blame. Arizona requires every driver to carry liability insurance, and it's that liability coverage, not a no-fault pool, that pays an injured person.¹ If you were hit in Phoenix, Tucson, or on a rural highway, your claim runs against the person who caused it.

That one design choice drives everything that follows: who you file against, how partial fault cuts your recovery, how much money is realistically on the table, and how fast you have to move.

What at-fault actually means here

In a no-fault state, an injured driver turns first to their own PIP coverage for medical bills up to a set limit, and the right to sue the other driver is restricted until you clear a threshold. Arizona does neither. There's no required PIP product to fall back on, and no injury threshold to cross before you can hold the other driver responsible. You build a claim against the at-fault driver's bodily injury liability coverage, and if that isn't enough, against your own uninsured or underinsured motorist coverage.

Because fault decides who pays, the proof of fault matters from day one: the officer's narrative, scene photos, witness accounts, and the Arizona crash report.

Partial fault doesn't end your claim

Being partly to blame does not knock you out. Under A.R.S. § 12-2505, when a jury finds you share fault, your case "is not barred," and your damages are reduced in proportion to your share.² Arizona is a pure comparative negligence state, so that reduction applies no matter how high your percentage climbs. A driver found 30% at fault for a $100,000 loss still recovers $70,000.² Someone found 90% at fault can still collect the remaining 10%. Many states cut you off entirely once you pass 50% or 51%; Arizona does not.

There are two edges to this. The statute takes comparative negligence away from anyone who "intentionally, wilfully or wantonly" caused or contributed to the injury.² And under A.R.S. § 12-712, if you were hurt while attempting or committing a felony (and in some cases a misdemeanor) and a jury finds you at least 50% responsible for your own harm, the defendant can be found not liable at all.³

The minimum insurance behind an at-fault claim

Since the at-fault driver pays, their policy limits often decide what you can actually collect. Arizona sets the floor at 25/50/15: $25,000 for bodily injury or death of one person, $50,000 for all bodily injury in one accident, and $15,000 for property damage. Those limits apply to every policy issued or renewed on or after July 1, 2020; older policies carried the previous 15/30/10 floor.¹

These are minimums, not what a careful driver usually buys. A single ambulance ride and an ER workup can pass $25,000 on their own. When someone carrying only state-minimum coverage causes a serious injury, that policy empties fast, and the rest of your recovery has to come from somewhere else.

When the other driver has too little insurance, or none

Arizona won't make you buy uninsured (UM) or underinsured (UIM) motorist coverage, but it makes your insurer offer it. Under A.R.S. § 20-259.01, an insurer must offer UM and UIM in writing at limits equal to your policy's bodily injury liability limits, and you can only reject them or take lower limits by putting it in writing.⁴ UM pays when the at-fault driver has no insurance; UIM fills the gap when they have some but not enough.

That coverage carries real weight in an at-fault state. The Insurance Research Council estimated that 15.4% of U.S. drivers were uninsured in 2023, and roughly one in three were uninsured or underinsured.⁵ When the other driver's policy is what stands between you and your medical bills, your own UM/UIM is often the difference between a paid claim and an empty one. Pull your declarations page and check; if you waived it years ago, you can add it back.

Paying medical bills while fault gets sorted out

With no PIP, Arizona gives you no automatic fund for early treatment. While the liability claim is pending, the bills usually run through your health insurance, through optional medical payments (med-pay) coverage if you bought it, and finally through the settlement or judgment against the at-fault driver.

Med-pay is a voluntary add-on, not a coverage the insurer has to offer the way it must offer UM/UIM. If your insurer pays med-pay benefits and later wants reimbursement out of your recovery, A.R.S. § 20-259.01 caps that lien to the amount paid over $5,000 for accidents after December 31, 1998, and requires the insurer to compromise the lien fairly.⁴ For the car itself, including a diminished-value claim once repairs are finished, see diminished value in Arizona.

Fault can reach past the other driver

An at-fault system can hold more than one party responsible. If a bar or store served alcohol to an obviously intoxicated patron, or sold to someone under 21 without asking for identification, and that drinking was a proximate cause of the crash, A.R.S. § 4-311 lets the injured person bring a dram-shop claim against the licensee.⁶ Employers of on-duty drivers, vehicle owners, and public road authorities can carry a share of fault too. Pinning down every responsible party is part of building a claim, and it's one reason people find an attorney instead of negotiating with an adjuster alone.

Deadlines that control an at-fault claim

Fault means nothing if you miss the filing window. Arizona gives you two years from the crash to sue for personal injury, and the same two years for damage to your vehicle, under A.R.S. § 12-542.⁷

Claims against a government defendant run on a much shorter clock. If a city bus, a state truck, or an on-duty public employee caused your crash, A.R.S. § 12-821.01 requires you to serve a written notice of claim within 180 days of the crash, and a notice filed late is barred.⁸ The lawsuit itself then has to be filed within one year, not two, under A.R.S. § 12-821.⁹ You can lose a government claim months before the ordinary two-year deadline was ever in play.

Arizona's at-fault rules reward two habits: documenting fault early and knowing your own policy. The other side will look hard for a percentage of fault to hang on you, because under pure comparative negligence every point it proves is money off your recovery.

This article is general information about Arizona law, not legal advice.

Sources

1. Arizona State Legislature, A.R.S. § 28-4009 (mandatory motor vehicle liability insurance and minimum limits). https://www.azleg.gov/ars/28/04009.htm

2. Arizona State Legislature, A.R.S. § 12-2505 (comparative negligence). https://www.azleg.gov/ars/12/02505.htm

3. Arizona State Legislature, A.R.S. § 12-712 (claimant harmed while engaged in a felony or certain misdemeanors). https://www.azleg.gov/ars/12/00712.htm

4. Arizona State Legislature, A.R.S. § 20-259.01 (uninsured and underinsured motorist coverage; medical payments liens). https://www.azleg.gov/ars/20/00259-01.htm

5. Insurance Research Council, "One in Three Drivers Are Either Uninsured or Underinsured in the U.S." (reporting 2023 estimates). https://insurance-research.org/news/one-three-drivers-are-either-uninsured-or-underinsured-us-exposing-themselves-and-other

6. Arizona State Legislature, A.R.S. § 4-311 (licensee liability for furnishing alcohol; dram shop). https://www.azleg.gov/ars/4/00311.htm

7. Arizona State Legislature, A.R.S. § 12-542 (two-year limitation for injury to person and property). https://www.azleg.gov/ars/12/00542.htm

8. Arizona State Legislature, A.R.S. § 12-821.01 (notice of claim against public entities and public employees). https://www.azleg.gov/ars/12/00821-01.htm

9. Arizona State Legislature, A.R.S. § 12-821 (one-year limitation for actions against public entities). https://www.azleg.gov/ars/12/00821.htm