Two questions that sound alike can produce very different answers in a Missouri injury case:

How much of the harm did each person cause? That is the comparative-fault question.
Who can actually be required to pay the judgment? That is a collection question governed in part by Missouri's joint-and-several-liability statute.

Keeping those questions separate is the key to understanding case value. A plaintiff's percentage of fault can reduce the damages award, while the defendants' percentages can determine how much of the resulting judgment may be collected from each defendant.

Pure Comparative Fault: Missouri's System

Missouri's Supreme Court adopted pure comparative fault in Gustafson v. Benda, 661 S.W.2d 11 (Mo. banc 1983), “insofar as possible.” The court's current Missouri Approved Instructions commentary confirms both the rule and its source.

For an ordinary negligence claim, the jury determines total compensatory damages and allocates fault. The court then reduces the plaintiff's damages by the plaintiff's percentage. Missouri does not use the 50- or 51-percent plaintiff-fault cutoff found in modified-comparative-fault states. A plaintiff assigned 90 percent of the fault would receive 10 percent of the damages found, assuming the plaintiff proves the claim and no separate rule changes the result.

For example:

Total compensatory damages found: $300,000
Plaintiff's allocated fault: 25 percent
Damages after comparative fault: $225,000

That arithmetic is only an illustration. It does not account for liens, settlements, insurance limits, litigation expenses, collectability, statutory caps that may apply to a particular claim, or other case-specific issues.

What the Jury Is Actually Comparing

A percentage is not supposed to emerge from intuition alone. Each side must connect conduct to a legally recognized duty and then connect the breach to the occurrence or injury. Useful case analysis therefore separates four propositions:

Duty: What rule of reasonable care or specific safety law applied?
Breach: What did a person do or fail to do?
Causation: Did that conduct contribute to the collision or the claimed injury?
Allocation: How should the causally relevant conduct be compared?

This structure exposes weak fault arguments. Evidence that a driver was speeding, for example, matters only if the evidence can support a finding that the speed contributed to the collision or harm. A fact that sounds careless is not automatically a percentage of legal fault.

Build the Evidence Around a Timeline

The strongest fault analysis usually reconstructs a timeline rather than collecting disconnected facts:

Before the event: lane position, speed, visibility, traffic controls, warnings, and each person's opportunity to perceive the danger.
During the event: reaction time, steering, braking, impact sequence, and the conduct alleged to be negligent.
After the event: vehicle positions, photographs, witness observations, medical findings, and preservation or loss of electronic evidence.

Potential evidence includes photographs, video, measurements, vehicle data, phone records obtained through lawful process, witness accounts, dispatch records, medical records, and qualified expert analysis. A police report can identify witnesses and record observations, but an officer's conclusion does not itself decide civil fault, and admissibility depends on the particular statement and purpose for which it is offered.

Preservation matters because many sources are temporary. Businesses overwrite surveillance footage, vehicles are repaired or destroyed, and event data may be lost. A prompt, targeted preservation request can be more valuable than a much broader request sent too late.

Test Every Plaintiff-Fault Theory for Causation

Common allegations include speeding, distraction, unsafe lane movement, failure to keep a lookout, and following too closely. Each should be tested adversarially:

What admissible evidence establishes the conduct?
What is the time-and-distance theory connecting it to the collision?
Does the physical evidence fit that theory?
Is the alleged conduct a cause of the event, a cause of additional injury, or neither?
What evidence would disprove the theory?

Phone records illustrate the point. A timestamp near a crash may justify investigation, but it does not by itself establish who handled the device, what the driver was doing at the critical moment, or whether any use contributed to the crash. The records, testimony, device evidence, and crash timeline must be reconciled.

A Seatbelt Is a Separate, Statutory Analysis

Missouri's seatbelt statute, RSMo § 307.178, draws unusually precise lines for motor-vehicle cases:

Seatbelt nonuse generally is not evidence of comparative negligence.
It may be admitted to mitigate damages only after expert evidence connects the nonuse to the injuries claimed.
Any resulting reduction is capped at one percent of the damages remaining after comparative-negligence reductions.
A separate subsection governs actions arising from a vehicle's design, manufacture, distribution, or sale, so the general one-percent description should not be transplanted into a vehicle-products case.

This is a useful model for legal analysis: classify an argument before calculating it. A contention about causing the crash, aggravating an injury, and failing to reduce later loss may require different evidence and instructions.

Failure to Mitigate Is Not the Same Event

A failure-to-mitigate theory usually concerns avoidable loss after the defendant's wrongful conduct, such as an unreasonable failure to obtain or follow appropriate treatment. It should not be used as a vague label for every disagreement about medical care. The defense still needs evidence identifying what reasonable step was omitted and what additional damages the omission caused.

Pre-existing conditions present another distinct causation problem. The questions are what condition existed before the event, what changed, and which claimed damages the event caused or aggravated. Comparing pre-event and post-event records is more useful than assuming that a prior diagnosis either defeats the claim or makes every later symptom compensable.

Multiple Defendants: Allocation Is Not Collection

Missouri's joint-and-several-liability statute, RSMo § 537.067, addresses payment responsibility after fault is found:

A defendant assigned 51 percent or more of the fault is generally jointly and severally liable for the judgment against the defendants.
A defendant below 51 percent is generally responsible only for that defendant's percentage.
The statute identifies exceptions involving an employee's fault and duties arising under the Federal Employers' Liability Act.
Punitive damages are several only under the statute.
The statute says the effect of its collection rule may not be disclosed to the factfinder.

Consider a simplified example with $500,000 in damages after accounting for the plaintiff's fault. If Defendant A receives 60 percent and Defendant B receives 40 percent of the defendants' allocated fault, § 537.067 may make A jointly and severally liable while B remains severally liable. But settlement credits, agency relationships, insurance, solvency, party status, and claim-specific statutes can change the practical result. Allocation math is not a substitute for a collection analysis.

Products Liability Has Its Own Statutory Definition of Fault

General negligence doctrine should not be copied mechanically into a products case. RSMo § 537.765 expressly applies pure comparative fault to products-liability claims, but limits plaintiff “fault” for that section to six listed categories. They include specified forms of unanticipated or unreasonable use, voluntary exposure to a known danger, failure to take precautions a reasonably careful user would take, and failure to mitigate damages.

That statutory list makes issue classification important. The exact claims pleaded—and the conduct the defense seeks to compare—determine which analysis applies.

A Better Way to Evaluate Settlement Risk

A serious evaluation uses ranges rather than a single confident percentage:

Estimate a supportable low, middle, and high range for total damages.
Estimate a supportable range for plaintiff fault, tied to identified evidence.
Apply the reduction to each damages scenario.
Analyze each defendant's payment responsibility, insurance, and collectability.
Account separately for liens, costs, delay, evidentiary risk, and the possibility of no recovery.

This does not predict a verdict. It makes assumptions visible. If one disputed fact changes the expected range dramatically, that fact deserves priority in discovery or investigation.

Practical Evidence-Preservation Checklist

Photograph the scene, vehicles, visible injuries, traffic controls, sight lines, and relevant conditions when it is safe to do so.
Preserve original files and metadata; do not edit the only copy.
Identify witnesses and obtain reliable contact information.
Request available incident and dispatch records.
Do not repair or dispose of important physical evidence before counsel evaluates preservation duties.
Seek appropriate medical care and give providers an accurate history.
Avoid public posts about the event, injuries, activities, or settlement.
Ask promptly whether a preservation letter, vehicle inspection, or court-authorized discovery is warranted.

For a collision-specific checklist, see what to do after a car accident in Missouri. For damage analysis, see how pain and suffering is valued and lost wages and earning capacity.

FAQ

Can I recover if I was mostly at fault?

In an ordinary negligence case, pure comparative fault does not impose a 50- or 51-percent plaintiff-fault bar. If total damages are $200,000 and the plaintiff is assigned 80 percent of the fault, the comparative-fault calculation leaves $40,000. Other defenses, proof requirements, costs, liens, and collection issues still matter.

Does the police report determine fault?

No. An officer does not decide civil liability at the scene. A report may preserve observations, measurements, statements, citations, and witness information, but whether a particular part is admissible depends on evidence rules and the purpose for which it is offered.

Can comparative fault be applied to passengers?

A passenger is not assigned fault merely for being present. But a passenger's own conduct can become relevant if evidence supports a duty, breach, and causal connection to the harm. The analysis is fact-specific.

How does comparative fault work in a rear-end collision?

The vehicle positions are important evidence, not an automatic percentage. The analysis may include following distance, speed, visibility, brake lights, traffic conditions, the reason for any stop, and whether either driver had a reasonable opportunity to avoid the collision.

Does Missouri's comparative fault apply to all types of cases?

No single summary safely covers every cause of action. General negligence, products liability, medical-negligence claims, intentional torts, statutory claims, and claims involving immunities or special defenses can have different rules. The pleaded claim and current governing law must be checked before applying the ordinary negligence formula.

Primary Authorities

Authorities checked July 21, 2026. Statutes and court instructions can change; verify the current text and the law governing the date and type of claim.

If disputed fault materially changes the value or collectability of your claim, contact Ott Law Firm or call (314) 710-2740 for a case-specific evaluation.

This article is for informational purposes only and does not constitute legal advice. Every case is different. Contact Ott Law Firm at (314) 710-2740 for a free consultation specific to your situation.

Comparative Fault in Missouri: How It Affects Your Recovery