Idaho Comparative Fault Law

Idaho uses modified comparative negligence—also called comparative fault—to decide what happens when an injured person and another party share responsibility for an injury. The rule can affect both whether an injured person may recover damages and how much of an award may be collected.

Under Idaho Code § 6-801, an injured person may recover from a person whose responsibility is greater than the injured person’s, but any damages allowed are reduced by the injured person’s percentage of responsibility. In a typical claim against one other party, a 50/50 allocation does not permit recovery from that party. Claims involving several responsible people require a party-by-party analysis.

What Is Comparative Fault?

Comparative fault is a method of assigning responsibility when more than one person’s conduct contributed to an injury. Instead of treating every accident as entirely one person’s fault, the factfinder assigns a percentage of responsibility to each person whose conduct legally caused the harm.

The terms comparative fault and comparative negligence are often used to describe the same allocation process. Idaho’s statute uses the phrases “contributory negligence” and “comparative responsibility,” but it does not apply the traditional all-or-nothing contributory-negligence rule to ordinary negligence claims covered by the statute. Our separate guide explains how contributory negligence compared with comparative fault.

Idaho’s Modified Comparative-Negligence Rule

Idaho’s rule has four central parts:

• An injured person’s responsibility is compared with the responsibility of the person from whom recovery is sought.
• The injured person may recover from that person only when the injured person’s responsibility is lower.
• Any damages allowed are reduced in proportion to the injured person’s percentage of responsibility.
• When several people share responsibility, Idaho law generally requires an individual comparison with each person from whom recovery is sought.

This is called a “modified” comparative-negligence system because partial responsibility does not always prevent recovery, but it can do so when the statutory comparison is not satisfied.

What Happens When Fault Is Split 50/50?

Section 6-801 says the injured person’s responsibility must be “not as great as” the responsibility of the person from whom recovery is sought. Equal responsibility is not lower responsibility. Therefore, in a typical claim involving one injured person and one other responsible party, a 50/50 allocation does not permit the injured person to recover from that party.

The familiar statement that a claimant must be “less than 50 percent at fault” is accurate for that ordinary two-party illustration. It should not be used as a shortcut for every multi-party case because Idaho law compares the claimant with each person individually.

How Shared Fault Reduces Damages

Consider a simplified claim against one other party. Suppose the proven damages are $100,000, the injured person is assigned 20 percent of the responsibility, and the other party is assigned 80 percent. The injured person’s responsibility is lower, so the statutory comparison is satisfied. The allowed damages are then reduced by 20 percent, producing an $80,000 award before any other case-specific issues are considered.

If the same two people were each assigned 50 percent, the injured person would not recover from that other party under section 6-801 because the injured person’s responsibility would be equal, not lower.

How Are Fault Percentages Determined?

Before a lawsuit, the injured person, the other parties, and their insurers may disagree about how responsibility should be allocated. If the dispute goes to trial, the judge or jury evaluates the evidence and applies the governing instructions. No single document automatically decides civil responsibility.

Evidence commonly considered in a shared-fault dispute may include:

• photographs and video of the event and surrounding conditions;
• witness accounts;
• physical evidence, vehicle damage, or property conditions;
• applicable safety rules and evidence of a violation;
• medical records bearing on causation and the timing of the injury;
• electronic data, business records, or maintenance records; and
• expert analysis when technical or medical issues are disputed.

In a car accident claim, for example, a police report may contain useful observations, but the report itself does not necessarily bind an insurer, judge, or jury on the final allocation of civil responsibility.

For a car-specific application, read how comparative fault affects an Idaho car accident claim.

What Changes When Several Parties Share Fault?

Claims involving several responsible people require more than adding everyone else’s percentages together and asking whether the injured person is below 50 percent overall. Under Idaho Code § 6-803(3), the injured person’s responsibility is generally compared individually with the responsibility of each party. A separate judgment is entered against a qualifying party for that party’s proportionate share of the total damages awarded.

That structure can matter in a multi-vehicle crash, a claim involving a property owner and contractor, or another event in which several people or businesses may have caused the same injury. The availability and amount of recovery can depend on the percentages assigned to each person, the legal theory asserted, and any statutory exception.

Where Can Comparative Fault Arise?

Comparative responsibility may arise in motor-vehicle collisions, unsafe-property cases, professional-negligence claims, and other actions in which the injured person’s own conduct is alleged to have contributed to the harm. Whether the defense is legally available—and what conduct may be compared—depends on the claim and facts.

A person does not lose a claim merely because an insurer alleges shared fault. The allegation still must be supported by evidence and connected to the injury under the governing law.

How Insurers Use Comparative-Fault Arguments

An insurer may argue that the injured person failed to pay attention, ignored a warning, delayed seeking treatment, violated a safety rule, or otherwise contributed to the event or the resulting harm. A higher percentage assigned to the injured person can reduce the amount the insurer offers. In a qualifying one-defendant case, an allocation equal to or greater than the other party’s can eliminate recovery from that party.

Those arguments are not automatically correct. Photographs, video, witness statements, medical records, and other contemporaneous evidence may show that the proposed percentage is unsupported or that the alleged conduct did not cause the injury.

What Should I Do If Someone Says I Was Partly at Fault?

• Describe the facts accurately without guessing about legal responsibility.
• Preserve photographs, video, messages, records, damaged property, and witness contact information.
• Obtain appropriate medical care and follow reasonable treatment instructions.
• Understand who an insurance adjuster represents and any applicable policy obligations before providing a recorded statement.
• Avoid posting about the event, your injuries, or your activities on social media while the claim is disputed.
• Ask an Idaho personal-injury attorney to evaluate the evidence and the proposed allocation of responsibility.

Frequently Asked Questions About Idaho Comparative Fault

Are comparative fault and comparative negligence the same thing?

The terms are commonly used interchangeably to describe the allocation of responsibility. Idaho Code section 6-801 uses “contributory negligence” and “comparative responsibility,” while courts and lawyers also refer to comparative negligence or comparative fault.

Can I recover damages if I was partly at fault?

Possibly. Under section 6-801, the injured person’s responsibility must be lower than the responsibility of the person from whom recovery is sought. Any damages allowed are then reduced by the injured person’s percentage of responsibility.

Who decides the percentages of fault?

The parties and insurers may negotiate percentages during a claim. If the dispute is litigated, the judge or jury determines responsibility from the admissible evidence and the court’s legal instructions.

Does comparative fault apply only to car accidents?

No. The rule can arise in different negligence and comparative-responsibility actions. Its application depends on the cause of action, the parties, and the facts.

Discuss a Shared-Fault Claim With Attorneys of Idaho

If an insurer or another party claims you share responsibility for an injury in Boise, Ada County, the Treasure Valley, or elsewhere in Idaho, the percentage assigned to you may materially affect the claim. The personal-injury team at Attorneys of Idaho can review the evidence, explain how the statutory comparison may apply, and discuss your available options.

Call 208-314-8888 or request a free consultation.