Idaho Motorcycle Laws: Helmets, Lane Sharing and the 50% Rule

Idaho gives adult riders a lot of freedom on helmets, but its fault rule is strict and its lane rules are narrower than some riders expect. This guide explains the main Idaho motorcycle laws and what they mean if you are hurt in a crash, with links to sources so you can check each point yourself.

Idaho motorcycle rules of the road

Licensing

To ride legally in Idaho, you need a valid driver license with a motorcycle endorsement, or a motorcycle instruction permit. You must also register the motorcycle, carry liability insurance and carry proof of it while riding.

Helmets

Idaho Code section 49-666 says no one under 18 may operate or ride on a motorcycle unless wearing a protective safety helmet that meets the state's standards. Riders and passengers 18 and older are not required to wear one. There are limited exceptions, for example riding on private property.

Eye protection

Summaries disagree on whether Idaho requires eye protection for adult riders, so check the current Idaho Motorcycle Operator's Manual before you rely on any one source. Eye protection is strongly recommended in any case.

Lane splitting and lane filtering

The Idaho State Police and the state's motorcycle safety program say that a motorcycle may share a lane only with one other motorcycle, and that lane sharing, lane splitting and lane filtering with any other vehicle are illegal in Idaho. A few websites claim Idaho legalized lane filtering, but the official Idaho sources say otherwise. Insurers often argue that a rider who was riding between vehicles is mostly or entirely at fault, so this rule can affect a claim.

Insurance

Idaho requires liability insurance of at least $25,000 for injury or death to one person, $50,000 per accident and $15,000 for property damage. Idaho is a fault-based state with no mandatory PIP or no-fault system, so check your own policy for medical payments coverage and for uninsured and underinsured motorist coverage. Those minimum limits can be small compared with a serious motorcycle injury.

Idaho motorcycle accident law

The deadline to file is 2 years

Under Idaho Code section 5-219(4), most personal injury actions must be filed within 2 years. A wrongful death action also has a 2-year deadline, counted from the date of death. Property damage claims, such as damage to your motorcycle, generally have a longer deadline of 3 years under section 5-218.

The 50% fault bar

Under Idaho Code section 6-801, Idaho follows modified comparative negligence. If your share of fault is less than 50%, you can recover, but your damages are reduced by your percentage of fault. If you are found 50% or more at fault, you recover nothing.

• 20% at fault: you can recover, reduced by 20%.
• 49% at fault: you can still recover, reduced by 49%.
• 50% at fault: recovery is barred.

As an illustration only, if damages are valued at $100,000 and a jury assigns you 20% of the fault, your recovery would be reduced to $80,000.

The cap on noneconomic damages

Idaho Code section 6-1603 caps noneconomic damages, such as pain and suffering, in personal injury cases. The cap is adjusted every year, and it was about $490,000 as of July 2024. Economic damages, such as medical bills and lost income, are not subject to that cap. Ask a lawyer for the current figure and any exceptions.

Helmets and your claim

Because adults are not required to wear a helmet in Idaho, going without one is not a legal violation for them, and a defendant generally has no statutory basis to cut your damages for that choice. An insurer may still argue that it made a head injury worse. For riders under 18, a missing helmet breaks the law and could be raised on the question of fault. Keep your helmet and eyewear after a crash and ask a lawyer how these arguments would be handled in your case.

What to do after a motorcycle crash in Idaho

• Get medical care promptly and describe every symptom, even ones that seem minor.
• Photograph the scene, your bike, your gear and your injuries.
• Save camera footage from a helmet cam, a dash cam or nearby businesses.
• Keep your helmet, eyewear, jacket and damaged gear instead of throwing them away.
• Collect witness names and ask for the police report number.
• Do not discuss fault with the other driver's insurer until you have spoken with a lawyer.
• Write down your deadlines, including the 180-day notice if a public entity may be involved.

When to talk to a lawyer

A free consultation can help you understand your deadlines, your insurance options and how the 50% bar may be argued. If you decide to hire someone, confirm that the lawyer is licensed in Idaho, ask for the fee agreement in writing and understand how case expenses are handled before you sign.

Frequently asked questions