Comparative negligence
Comparative negligence is a rule that splits fault among parties in a civil claim and reduces each side's recovery by its share of the fault.
Collision Bureau is not a law firm and this is not legal or medical advice. It is general information about what happens after a crash. For advice on your situation, talk to an attorney licensed in your state or a treating clinician.
What it means
Comparative negligence is a civil-law rule for crashes where more than one party acted carelessly. Instead of assigning the whole claim to one driver and nothing to the other, the rule assigns a percentage of fault to each party involved and reduces each party's recovery by its own percentage. The core idea is apportionment: a claim is not a single yes or no, it is a split that both numbers have to add up to one hundred.
How the math works in general terms
Picture a claim valued at ten thousand dollars where the claimant is found 20 percent at fault. Under a pure version of the rule, the recovery is reduced by 20 percent to eight thousand dollars. Under a modified version, the same reduction applies up to a cutoff, usually set at fifty or 51 percent, and a claimant above that line recovers nothing. The specific cutoff and the specific version of the rule in effect depend on where the claim is brought, which is a state-law question an attorney answers.
Where it comes up in a crash
The percentages do not wait for a trial to appear. An adjuster assigns a working number during claim handling, often as a direct result of the police narrative, the photos, and the damage patterns on the vehicles. That number drives the offer. If the file settles, the recovery is the claim value times one minus the agreed percentage. If the file is tried, a judge or a jury sets the percentage based on the evidence presented, and the math runs again on whatever value a verdict places on the loss.
What it is not
Comparative negligence is not the same as contributory negligence, which is a stricter rule that bars recovery entirely when the claimant carries any fault at all. It is not a rule about criminal liability. It is not applied by the police at the scene, who may document a cause and issue a citation but do not legally bind an insurer or a court. And it is not a formula you can compute from your own view of the crash. The percentage emerges from evidence that other people assemble and read, which is why that record matters more than any single opinion of the day.
Questions people actually ask
01Does my own share of fault end my claim?
Not by itself under a comparative-negligence rule. The rule reduces a recovery by the share of fault assigned to the claimant rather than eliminating it, except where a modified version of the rule cuts off recovery above a stated percentage. Which version applies, and what percentage the facts of your crash would support, are state-law questions that a licensed attorney in your state answers against your specific record, not something a general-information page can determine.
02Who decides my percentage of fault?
In practice an adjuster assigns a working percentage during claim handling, which is a negotiation input, not a legal finding. If the claim becomes a lawsuit, the percentage is decided by a judge or a jury against the evidence, which can be lower or higher than the number used in negotiation. The police report may influence the opening percentage but does not control it, and neither side's own view of the facts controls it.
03What if we both think the other person is wrong?
That is the ordinary condition in which the rule exists. Comparative negligence does not require agreement. It requires evidence, which is why photos of the scene, the police narrative, the vehicle damage patterns, and any witness statements end up carrying the apportionment conversation. Where those sources diverge, a formal process like mediation, arbitration, or trial becomes how the percentage gets settled. The right process for a specific disagreement is a question for an attorney.