If you were partly to blame, the rule your state uses can reduce your recovery proportionally — or eliminate it completely. Which rule applies frequently matters more to the outcome than the severity of the injury.
The three systems
Pure comparative negligence. Damages are reduced by your percentage of fault, and you recover something even at 90% at fault. A $100,000 award with 30% fault becomes $70,000.
Modified comparative negligence. The same proportional reduction, but with a bar. In some states you recover nothing once you reach 50%; in others the bar is 51%. That single percentage point is the difference between a reduced award and none at all, which is why fault apportionment is fought so hard in these states.
Contributory negligence. A small minority of jurisdictions still apply the harshest rule: any fault at all, even 1%, bars recovery entirely. Doctrines such as last clear chance exist to soften it, but the starting position is severe.
How fault gets assigned
The jury assigns percentages after hearing the evidence. There is no formula. Typical arguments include speed, attention, whether a seat belt or helmet was used, whether a hazard was open and obvious, and whether the claimant ignored a warning or instruction.
Some states restrict certain arguments — seat belt evidence is limited or excluded in a number of jurisdictions, for example — so what the defence may even raise is itself a state-law question.
Several defendants, and who pays
With multiple defendants, apportionment interacts with joint and several liability. Under a joint-and-several rule a single defendant can be liable for the whole judgment regardless of their share. Under a several-only rule each pays their percentage, so an insolvent or uninsured defendant’s share is simply lost to the claimant. Many states apply a hybrid, switching approaches above a fault threshold.
Empty-chair defences follow from this: pointing at an absent party who cannot respond is a way of moving percentages away from the defendant in the room.
Why it drives settlement
Fault is the most uncertain variable in most negotiations. In a modified state near the bar, a few percentage points swing the case between full-ish value and nothing, and both sides discount heavily for that risk. Adjusters raise comparative fault early precisely because it reduces the number without disputing the injury itself. See Negligence and how lawyers weigh settling against trial.
General information only, not legal advice. Which system applies, and how it interacts with joint liability, is determined by state law.