Very few car accidents involve one driver who did everything right and one who did everything wrong. Most crashes involve some degree of shared responsibility, and in Illinois, how that responsibility gets divided can determine not just how much compensation a person receives, but whether they receive anything at all.
This guide covers:
- Illinois’s modified comparative negligence rule and its 50% threshold
- How a fault percentage actually gets assigned and why it can change
- What happens to a claim’s value once shared fault is factored in
- A separate rule that applies specifically when more than one party is at fault
At a Glance
| Fault Percentage | Outcome |
| 0% (not at fault) | Full compensation available |
| 1% to 50% | Compensation available, reduced by your percentage of fault |
| 51% or more | Barred from recovering any compensation |
| Exactly 50% | Still eligible; compensation reduced by half |
Illinois’s Modified Comparative Negligence Rule
Illinois follows what is known as modified comparative negligence, governed by 735 ILCS 5/2-1116. Under this rule, a person who is partly responsible for a car accident can still recover compensation, but only if their share of fault does not exceed 50 percent. Once a person’s fault reaches 51 percent or more, Illinois law bars them from recovering anything, regardless of how much the other driver was also at fault.
For claims that fall within the recoverable range, the math is straightforward but consequential. A person’s compensation is reduced by their own percentage of fault. Someone found 20 percent at fault for a crash that resulted in $100,000 in damages would still be eligible to recover $80,000, while someone found 50 percent at fault under the same facts would recover only $50,000. The difference between 50 percent and 51 percent fault is not a small one on paper, since it is the difference between recovering half of a claim’s value and recovering nothing at all.
Illinois’s approach sits between two more extreme systems used elsewhere. A small number of states still follow pure contributory negligence, where any fault at all, even 1 percent, bars recovery entirely. Other states use pure comparative negligence, where a person can recover some compensation no matter how much fault they carry, even if they were more responsible for the crash than the other driver. Illinois’s modified system falls in the middle, allowing recovery for anyone at 50 percent fault or below while cutting off recovery entirely past that line, which makes the exact fault percentage assigned in a given case genuinely consequential rather than a minor detail.
How Fault Actually Gets Assigned
Fault in a car accident claim is not a fixed number handed down at the scene. It typically starts with an initial determination by the insurance companies involved, based on the police report, statements from those involved, witness accounts, and physical evidence from the crash. This initial percentage is not final. If a claim proceeds toward litigation and the parties cannot agree, a judge or jury makes the ultimate determination of fault at trial.
This matters because a fault percentage can shift meaningfully as a case develops. New evidence, additional witness statements, expert reconstruction of how the crash occurred, or documentation the insurer initially lacked can all move the needle in either direction. An insurer’s early fault assessment sometimes favors the insurer’s own position, since a higher fault percentage assigned to the injured person directly reduces what the insurer eventually has to pay. Because that initial number is a starting point rather than a final ruling, treating it as unchangeable can leave real compensation on the table.
The types of evidence that tend to shift a fault percentage are often things an injured person does not think to gather in the immediate aftermath of a crash. Traffic camera or dash camera footage, data pulled from a vehicle’s event data recorder, cell phone records suggesting distraction, and detailed statements from independent witnesses can all carry more weight than the drivers’ own competing accounts of what happened. A fault determination based only on the initial police report, without any of this additional evidence, is frequently incomplete rather than final, particularly in crashes where the initial responding officer did not witness the collision directly and relied primarily on what each driver reported at the scene.
When More Than One Party Shares Fault
Shared fault gets more complicated when more than two parties are involved, which is common in multi-vehicle crashes or collisions involving a commercial driver alongside other motorists. Illinois addresses this scenario through a separate statute, 735 ILCS 5/2-1117, governing joint and several liability among defendants. Under this rule, a defendant found to be 25 percent or more at fault can be held jointly and severally liable for the injured person’s non-medical damages, meaning that defendant can be pursued for the full amount rather than only their proportional share. A defendant found less than 25 percent at fault is only severally liable for non-medical damages, limited to their own percentage.
Medical expenses work differently and are treated separately from this threshold. Regardless of a defendant’s individual fault percentage, all defendants found liable in the case remain jointly and severally liable for the injured person’s past and future medical and medically related expenses. This distinction matters in cases with catastrophic injuries where medical costs make up a large share of total damages, since even a defendant found only a small percentage at fault can still be responsible for the full medical bill if that defendant is found liable at all. Anyone dealing with a crash involving multiple potentially at-fault parties is often well served speaking with why families pick Marker Law as their car wreck lawyer in Naperville early, since identifying every liable party and understanding how these overlapping fault rules apply can meaningfully affect what is actually recoverable.
Working through how comparative fault and joint liability interact is rarely something a person can accurately estimate on their own, particularly once more than one insurer is involved and each is independently motivated to minimize its own exposure. Firms such as Marker Law generally get involved early in these multi-party situations specifically because the fault allocation itself, not just the value of the underlying injuries, ends up shaping the final recovery.
Summary
Shared fault does not automatically disqualify someone from recovering compensation after an Illinois car accident, but it does change the math, and at 51 percent fault it eliminates the claim entirely. Fault is not fixed at the outset and can shift as evidence develops, and cases involving more than one at-fault party bring an additional layer of rules governing who can be pursued for the full recovery versus only a proportional share.
Key Takeaways
- Illinois’s 50 percent bar rule means fault up to 50 percent reduces a claim, but fault of 51 percent or more eliminates it entirely.
- An initial fault determination from an insurance company is a starting point, not a final ruling, and can change with new evidence.
- When multiple parties share fault, a separate rule can hold a defendant found 25 percent or more at fault responsible for the full non-medical recovery, while medical expenses remain jointly and severally liable for all liable defendants regardless of percentage.
Understanding exactly where a fault percentage lands, and how it interacts with claims involving more than one at-fault party, is often the difference between an accurate settlement and one that undervalues what is actually recoverable.
Frequently Asked Questions
What happens if I am found more than half at fault for a car accident in Illinois?
Under Illinois’s modified comparative negligence rule, a person found 51 percent or more at fault is barred from recovering any compensation, even if the other driver was also partially at fault.
Can I still recover compensation if I was partly at fault?
Yes, as long as your fault does not exceed 50 percent. Your compensation is reduced by your percentage of fault, so a person found 30 percent at fault on a $100,000 claim would recover $70,000.
Who decides my percentage of fault after a crash?
Insurance companies typically make an initial determination based on the police report, witness statements, and available evidence. If the case does not settle, a judge or jury makes the final determination at trial.
Can my fault percentage change during the claims process?
Yes. New evidence, additional witness statements, or expert analysis of how the crash occurred can shift the assigned fault percentage in either direction as a case develops.
What happens when more than one driver or party is at fault?
Under 735 ILCS 5/2-1117, a defendant found 25 percent or more at fault can be held responsible for the full amount of non-medical damages, while a defendant found less than 25 percent at fault is only responsible for their proportional share. All liable defendants remain jointly responsible for medical expenses regardless of their individual fault percentage.
Does exactly 50 percent fault bar my claim?
No. At exactly 50 percent fault, you remain eligible to recover compensation, though your award is reduced by half. The bar only applies once fault reaches 51 percent or more.
