Guide · Injury · Illinois

Illinois’s More-Than-50% Rule: How a Single Number Decides Your Injury Case

You can be in the right and still walk away with nothing. Here is how modified comparative negligence works, and why the insurer fights over your percentage from the first phone call.

By Lincoln Square Law · 7-minute read

Very few collisions, falls, or workplace injuries have a single cause. Illinois law accepts that reality, and it measures it with a number: the percentage of fault a judge or jury assigns to each person whose conduct contributed to the injury, including the person who was hurt. That number decides two things at once. It decides whether you recover anything at all, and it decides how much of your damages you keep. Because the stakes attach to a percentage rather than a yes-or-no verdict, the fight over fault starts long before trial, usually with the first call from an insurance adjuster.

The rule in one sentence

Under section 2-1116 of the Code of Civil Procedure, a plaintiff whose own fault is more than 50 percent of the proximate cause of the injury is barred from recovering damages, and a plaintiff whose fault is 50 percent or less recovers damages reduced in proportion to that fault (735 ILCS 5/2-1116). Lawyers call this modified comparative fault. It is sometimes described as a 51 percent bar, because the line is crossed only when the injured person’s share exceeds half.

The arithmetic is simple. Suppose a jury finds $200,000 in damages. At 20 percent fault, you recover $160,000. At 50 percent, you recover $100,000. At 51 percent, you recover nothing. A single point on either side of that line can be worth the entire case, which is why the defense rarely concedes fault it can plausibly shift.

Who decides the percentage, and when

The percentage is decided by the trier of fact: the jury in a jury trial, or the judge in a bench trial. It is not decided by the police report, and it is not decided by the insurer. Comparative fault is an affirmative matter the defense must raise and support with evidence. In practice, though, insurers form their own view of fault within days, and that view shapes every settlement conversation that follows. An adjuster who believes you were 40 percent at fault will discount every offer by at least that much, whether or not a jury would agree.

That is why the early record matters so much. The facts that eventually go to a jury are usually gathered, or lost, in the first few weeks.

How fault gets built from evidence

Fault percentages are argued from concrete proof: the physical damage to the vehicles and where it sits, skid marks and final rest positions, traffic signals and sight lines, photographs of the scene, crash data retrieved from the vehicles, surveillance and dashcam footage, witness accounts, phone records, and the statements of the people involved. Each piece either supports or undercuts a story about who did what, and in what order.

Some of that evidence disappears quickly. Private video is often overwritten within days. Vehicles are repaired or salvaged. Witnesses become hard to reach. A lawyer’s preservation letter can prevent some of that loss, and Illinois recognizes that a party on notice of a claim can face consequences for failing to preserve relevant evidence (Boyd v. Travelers Insurance Co., 166 Ill. 2d 188 (1995)). The letter only helps if it goes out in time.

Where percentages usually move

Your own words. The most common way an injured person’s percentage rises is through an early recorded statement to the other side’s insurer. Phrases like “I didn’t see them,” “I was running a little late,” or “I’m fine” are ordinary things to say after a shock. Months later they are read back as admissions. You are not required to give the other driver’s insurer a recorded statement.

Gaps in medical treatment. Failure to mitigate damages is a separate defense from fault, but it travels with it. If treatment stops for weeks, the defense argues that later problems were not caused by the incident, or that you made them worse.

Reconstruction. In serious cases, both sides may retain reconstruction experts who model speeds, timing, and perception-reaction. The quality of the physical evidence preserved early often decides which reconstruction a jury believes.

Seat belts. Illinois treats seat belt use differently from many states. The Vehicle Code provides that failure to wear a seat belt is not to be considered evidence of negligence and does not diminish a recovery for damages arising out of the ownership, maintenance, or operation of a motor vehicle (625 ILCS 5/12-603.1). Insurers sometimes raise the issue anyway in early negotiations. It should not move your percentage in court.

When more than one defendant is at fault

Many injuries involve several responsible parties: two drivers, a driver and a road contractor, a property owner and a snow removal company. Illinois addresses how the defendants share responsibility in section 2-1117. As a general rule, a defendant whose fault is less than 25 percent of the total fault attributable to the plaintiff, the defendants sued by the plaintiff, and any third-party defendant except the plaintiff’s employer is only severally liable for non-medical damages, meaning that defendant pays only its own share of those damages. Defendants at 25 percent or more are jointly and severally liable, and all defendants remain jointly and severally liable for past and future medical expenses (735 ILCS 5/2-1117).

That allocation affects strategy in practical ways. If the most responsible party has little insurance, whether a smaller defendant crosses the 25 percent threshold may determine how much of the verdict is actually collectible. It also affects who should be named in the lawsuit and how settlements with some defendants are structured.

How fault shows up in settlement talks

Most injury cases settle, so the percentage is usually argued across a table rather than decided by a jury. An insurer will rarely say “we think you were 35 percent at fault.” Instead the discount appears in the size of the offer and in the reasons given for it. Knowing how the evidence would likely be weighed lets you tell the difference between a fair discount for real risk and a number built on an assumption the record does not support. When the defense’s theory depends on a fact that can be disproved, such as a signal timing or a sight line, disproving it early changes the negotiation more than any argument about fairness.

What the percentage applies to

The reduction applies to the full measure of damages the jury finds, which in an injury case can include medical expenses, lost earnings and earning capacity, pain and suffering, disability, disfigurement, and loss of a normal life. The larger and better documented the damages, the more each percentage point is worth in dollars. Proving damages and defending the fault percentage are two halves of the same job.

Deadlines run alongside the fault fight

A strong position on fault does not help if the claim is filed late. The general limitations period for personal injury in Illinois is two years (735 ILCS 5/13-202). Claims against local public entities generally must be filed within one year (745 ILCS 10/8-101(a)), and other defendants, such as transit agencies, carry their own rules. The steps that protect your fault percentage in the first weeks, preserving evidence and avoiding careless statements, are the same steps that keep the deadline in view.

Practical steps if fault is disputed

• Write down your own account of what happened while it is fresh, including timing, lane positions, signals, and what you saw and heard. Keep it private and share it with your lawyer, not the insurer.
• Collect photographs, the crash report number, witness names, and any video you know exists, and note where cameras were located.
• Decline recorded statements to the other party’s insurer, and keep your own insurer’s questions to basic facts until you have advice.
• Keep every medical appointment and follow treatment recommendations, so the defense cannot turn a gap into an argument.
• Ask a lawyer to evaluate whether other parties share responsibility, which may change both the percentages and the coverage available.

An insurer’s first view of fault is a negotiating position, not a finding. With the evidence gathered early, it is often a position that can be moved.