Arizona Motorcycle Laws: ARS 28-964 + Insurance

Arizona motorcycle law sits in three places. The traffic code (Title 28). The civil liability framework (Title 12). The insurance code (Title 28, Chapter 9). Riders who get hurt need to understand all three because each one shapes what happens after a crash.

This guide explains the rules in plain language, with the actual statute citations.

Helmet Law: ARS 28-964

Arizona’s motorcycle helmet statute is short and specific. The text of ARS 28-964 requires:

• A DOT-approved helmet for any operator or passenger under 18
• Eye protection (goggles or face shield) for all operators if the motorcycle isn’t equipped with a windshield

That’s it. Adult riders aren’t legally required to wear a helmet. This is unusual at the national level. Most states have universal helmet laws. Arizona is one of about 28 states that allow adult riders to choose.

The law has practical consequences in personal injury cases beyond the statutory penalty.

For insurance and damages: A helmet wasn’t required, so the absence of one isn’t negligence per se under Arizona law. But it can still be argued as comparative fault if the head injuries would have been less severe with a helmet. Insurance defense lawyers use this argument routinely. Arizona courts have allowed evidence of non-helmet use to be considered by juries when assessing the severity of head injuries.

For criminal cases: Failure to comply with the under-18 helmet requirement is a civil traffic violation, not a criminal offense.

Insurance Requirements: ARS 28-4135

Arizona requires every motor vehicle (including motorcycles) to carry minimum liability insurance. The current minimums under ARS 28-4135 are:

• $25,000 bodily injury per person
• $50,000 bodily injury per accident
• $15,000 property damage

These are the floor. They aren’t the recommended coverage. They’re the minimum required to legally register and operate a motorcycle in Arizona.

For motorcyclists specifically, these limits are dangerously low. The medical cost of a serious motorcycle crash routinely exceeds $25,000. A multi-day hospital stay with surgery can hit six figures before the rider leaves the building.

If you’re hit by a driver carrying only the state minimums, the at-fault driver’s insurance will pay $25,000 toward your bodily injury claim and stop. Anything beyond that comes from your own pocket, your own underinsured motorist coverage, or a lawsuit against the driver personally.

Comparative Fault: ARS 12-2505

Arizona follows pure comparative fault under ARS 12-2505. What this means in practice:

A jury can assign a percentage of fault to every party involved in the crash, including the injured plaintiff. Damages are then reduced by the plaintiff’s percentage of fault. There is no cutoff that bars recovery.

A rider who is found 30% at fault for a crash can still recover 70% of their damages. A rider who is found 80% at fault can still recover 20% of their damages. Arizona is one of about a dozen pure comparative fault states. Most states use a “modified” rule that bars recovery if the plaintiff is more than 50% at fault.

For motorcycle cases specifically, comparative fault is where insurance companies focus their defense. Common arguments:

• “The rider was speeding”
• “The rider was lane-splitting” (illegal in Arizona)
• “The rider wasn’t wearing a helmet” (legal but used to argue contribution to head injuries)
• “The rider was wearing dark clothing”
• “The rider should have anticipated the turn”

Each of these arguments aims to assign a percentage of fault to the rider that reduces the recovery. A skilled motorcycle injury lawyer responds to each one with crash reconstruction, witness testimony, helmet use evidence (if applicable), and documentation of the at-fault driver’s failures.

A.R.S. 28-964: The Helmet Statute in Detail

The practical effect of A.R.S. 28-964 goes beyond the bare statutory text. Arizona’s helmet law has been in its current form since the legislature rolled back a universal helmet requirement decades ago. The under-18 requirement is enforceable by any Arizona law enforcement agency, and violations are classified as civil traffic infractions with a modest fine.

The more consequential impact shows up in civil litigation. Arizona courts, including Maricopa County Superior Court, routinely admit evidence of non-helmet use in motorcycle injury cases to allow the jury to allocate comparative fault on head injury severity specifically, even though non-use isn’t negligence per se.

Defense attorneys use this to knock 20 to 40 percent off head injury damages in many cases. A skilled plaintiff’s attorney responds by separating causation from severity.

The absence of a helmet didn’t cause the driver to turn left in front of the motorcycle. The helmet argument only affects the portion of damages attributable to head injuries, not the broader claim for broken bones, internal injuries, road rash, or lost wages.

Lane Splitting, Lane Filtering, and A.R.S. 28-903

Arizona prohibits lane splitting under A.R.S. 28-903. Riders can’t pass between cars in adjacent lanes while traffic is flowing.

Lane filtering, the narrower practice of moving past stopped vehicles at low speeds, became legal in 2022 under A.R.S. 28-903.01, but the conditions are strict: traffic must be stopped or slow-moving, the motorcycle must travel at 15 mph or less, and the posted speed limit must be 45 mph or lower.

Outside those specific conditions, moving between lanes is still illegal and creates a strong comparative fault argument if a crash occurs.

Lane splitting in flowing traffic remains legal in California, Utah (in some forms), Hawaii (under certain conditions), and a few other states. In Arizona, doing it in flowing traffic is a traffic violation, and defense attorneys will use it to assign fault percentage to the rider under the comparative negligence framework in A.R.S. 12-2505.

Why Maricopa County Superior Court Handles Most Motorcycle Cases

Most serious motorcycle injury and wrongful death cases in Arizona are filed in Maricopa County Superior Court because that’s where the population density, the highways, and the volume of at-fault drivers concentrate. The court handles civil claims with damages exceeding $10,000, which nearly every serious motorcycle injury case clears.

Wrongful death claims filed under A.R.S. 12-611 run through the same court, and the Arizona Constitution’s prohibition on damage caps (Article 2, Section 31) means the jury can award whatever the evidence supports.

Statute of Limitations: ARS 12-542

Arizona’s statute of limitations for personal injury is two years from the date of the injury. This is found in ARS 12-542 and applies to motorcycle crash cases.

Two important nuances:

Minors: If the injured rider is under 18, the clock doesn’t start until they turn 18. This is “minority tolling” under ARS 12-502. A minor injured at 14 has until age 20 to file.

Wrongful death: If a rider dies in the crash, the wrongful death claim accrues at death, not at the date of the underlying crash. The two-year clock starts on the date of death.

The two-year deadline is firm. Missing it generally means the claim is barred. There are very limited exceptions for fraudulent concealment and other equitable doctrines, but they rarely apply to motorcycle crash cases.

A.R.S. 28-4135 Insurance Minimums and Real-World Coverage Gaps

The state minimum of $25,000 bodily injury per person under A.R.S. 28-4135 is the figure Arizona drivers are statutorily required to carry. In practice, that minimum creates huge coverage gaps for motorcyclists who get hit by minimally insured drivers. A single ER visit, one night in the ICU, or a surgical repair of a compound fracture can exceed $25,000 before the rider’s own physical therapy starts.

When the at-fault driver’s policy is exhausted at that point, the rider’s recovery path shifts to the rider’s own UM/UIM policy under A.R.S. 20-259.01, which is why carrying meaningful UM/UIM coverage on a personal policy matters so much for Arizona motorcyclists. The $100,000/$300,000 UM/UIM recommendation isn’t aggressive. It’s the baseline for anyone serious about protecting their family.

Practical Implications

Arizona motorcycle law gives riders less legal protection than the laws of most states. The helmet law is permissive. The insurance minimums are low. The lane-splitting prohibition limits a defensive maneuver legal in other jurisdictions. The comparative fault rule allows defense lawyers to chip away at recovery by assigning percentages of blame.

The two things riders can do to protect themselves legally:

1. Carry significant UM/UIM coverage on your own policy. $100,000 per person and $300,000 per accident is a sensible floor for any rider. More is better. The cost difference is small relative to the protection it provides.

2. Document everything after a crash. Photos of the scene, the bike, the gear, and any visible injuries. Witness names and phone numbers. Police report number. Insurance information from every involved party. Don’t give a recorded statement to the at-fault driver’s insurance company before consulting an attorney.

The data on Arizona motorcycle fatalities, covered separately, shows why these protections matter. Arizona’s roads are unforgiving. The legal framework doesn’t bend to opinion. Riders who understand both can make informed choices about coverage, gear, and what to do after a crash.