By Charles N. Therman, Esq. | Principal Attorney & Founder, Therman Law Offices | Last reviewed: October 2026
Quick answer: Illinois uses two different fault percentages in many negligence cases. A plaintiff who is more than 50% at fault generally cannot recover under 735 ILCS 5/2-1116. A separate rule in 735 ILCS 5/2-1117 uses a 25% threshold to determine whether a liable defendant may be responsible only for that defendant’s share of certain nonmedical damages or may face joint-and-several liability for them. Past and future medical and medically related expenses are treated differently.
A three- or four-vehicle collision can look straightforward on a police diagram and become much more complicated once insurers, lawyers, and eventually a jury start assigning percentages of fault. One driver may have made the first unsafe lane change. Another may have been following too closely. A third vehicle may have entered the chain reaction seconds later. The injured person may also be accused of contributing to the crash.
Those percentages do more than decide who ’caused’ the wreck. Under Illinois law, they can change how much the injured person can recover and which defendant may be legally responsible for paying particular categories of damages.
Illinois Uses a 50% Rule for the Plaintiff
Illinois’s modified comparative-negligence rule appears in 735 ILCS 5/2-1116. If the plaintiff’s contributory fault is more than 50% of the proximate cause of the injury or damage, the plaintiff is barred from recovering. If the plaintiff is 50% at fault or less, recovery is reduced in proportion to the plaintiff’s percentage of fault.
That distinction matters. A plaintiff found exactly 50% at fault is not automatically barred under the statute; the award is reduced by 50%. The rule is therefore about the injured person’s right to recover and the reduction of that recovery.
The 25% Rule Answers a Different Question
A separate statute, 735 ILCS 5/2-1117, addresses joint liability among defendants in negligence and certain strict-product-liability cases. It does not replace the 50% rule. Instead, it helps determine how payment responsibility can be divided among defendants who are found liable.
For purposes of the 25% calculation, the statute looks at the total fault attributable to the plaintiff, the defendants sued by the plaintiff, and third-party defendants, while specifically excluding the plaintiff’s employer from that denominator.
Medical Expenses Are Treated Differently
Section 2-1117 makes a major distinction between medical expenses and other damages. All defendants found liable are jointly and severally liable for the plaintiff’s past and future medical and medically related expenses.
In practical terms, a liable defendant’s payment exposure for medical damages is not capped at that defendant’s individual percentage of fault under this provision. That can matter when one defendant has substantial insurance coverage and another has little or no collectible coverage.
This is one reason a multi-vehicle claim cannot always be valued by taking the total damages and simply multiplying the number by each driver’s fault percentage.
For Other Damages, 25% Is the Dividing Line
For damages other than the medical and medically related expenses covered by the first part of § 2-1117, the defendant’s percentage becomes especially important.
- A defendant found less than 25% at fault is generally severally liable for those other damages, meaning that defendant is responsible for the share corresponding to that defendant’s percentage.
- A defendant found 25% or more at fault is jointly and severally liable for those other damages under the statute.
Those other damages can include significant losses such as lost income, diminished earning capacity, disability, pain and suffering, and other compensable losses depending on the evidence and claims in the case.
Why 24% Versus 25% Can Matter
Consider a simplified example. An injured plaintiff is assigned 10% of the fault. Defendant A is assigned 24%, and Defendant B is assigned 66%.
The plaintiff’s 10% share reduces the plaintiff’s overall recovery under § 2-1116. Defendant A’s 24% share creates a different issue: because it is below the 25% threshold, Defendant A is generally severally liable for nonmedical damages under § 2-1117. If the factfinder instead assigned Defendant A 25%, the statute’s treatment of those nonmedical damages would change.
That is why a one-percentage-point dispute may have consequences far beyond the arithmetic on a verdict form.
Multi-Car Crashes Make Fault Allocation Harder
Chain-reaction collisions often create factual disputes that do not exist in an ordinary two-car crash. A lead driver may brake suddenly. A second driver may be too close to stop. A third may be distracted, speeding, or unable to see stopped traffic. Separate impacts can also create medical-causation disputes about which collision produced which injury.
Commercial vehicles, employers, vehicle owners, government entities, product manufacturers, or roadway defendants can add still more layers. The legal question is not simply whether another person was negligent; it is which parties belong in the fault allocation and what evidence supports each percentage.
FindAttorneys has separately explained the broader car accident compensation process in Chicago. In a multi-defendant case, § 2-1117 adds another step after damages are identified: determining which liable parties may be legally responsible for paying them.
The Plaintiff’s Employer Is Excluded From the 25% Denominator
One easily missed detail in § 2-1117 is the treatment of the plaintiff’s employer. The statute expressly excludes the plaintiff’s employer from the total fault used to determine whether a defendant falls below or reaches the 25% threshold.
That can matter when an employee is injured in a work-related crash and has a workers’ compensation claim while also pursuing a negligence action against another driver, trucking company, contractor, or other third party.
The employer’s conduct can still matter in other legal contexts, but the statutory calculation for this particular joint-liability threshold does not simply add the employer’s percentage to the denominator.
Settlements With One Defendant Can Affect the Rest of the Case
Illinois also has a Joint Tortfeasor Contribution Act. When two or more parties may be liable for the same injury, contribution rights and good-faith settlements can affect the relationships among settling and nonsettling defendants.
A good-faith settlement can discharge a settling tortfeasor from contribution liability to other tortfeasors. That means a partial settlement should be evaluated in the context of the entire case rather than as an isolated insurance payment.
The legal and financial effect can depend on the settlement amount, the parties who remain in the case, the fault ultimately assigned, and the categories of damages at issue.
Evidence Matters More Than the Police Report Alone
Police reports can be useful, but percentage allocation in a civil case is not determined by a single box on a crash report. In a serious multi-car collision, the evidence may include:
- vehicle positions, crush patterns, photographs, and scene measurements;
- traffic-camera, dash-camera, business-surveillance, or phone video;
- event-data-recorder or other vehicle data where available;
- 911 recordings, witness statements, and first-responder observations;
- cellphone or electronic evidence when distraction is disputed;
- commercial-driver records, employer policies, and vehicle-maintenance material when relevant;
- medical records and expert analysis addressing which impact caused or aggravated particular injuries; and
- accident-reconstruction analysis in cases where the sequence of impacts is disputed.
For someone comparing representation after a serious Cook County collision, a neutral place to evaluate what a local firm says it handles is the page for Choose Charlie car accident attorneys Chicago. The useful question is not the marketing label, but whether counsel can identify all potentially responsible parties, preserve time-sensitive evidence, and explain how Illinois’s 50% and 25% rules may interact with the facts.
Illinois Usually Gives Two Years for a Personal-Injury Lawsuit
Under 735 ILCS 5/13-202, an action for damages for injury to the person generally must be commenced within two years after the cause of action accrues.
Exceptions and different deadlines can apply depending on the defendant and circumstances, including some claims involving government entities or minors. Insurance negotiations do not automatically extend the filing deadline.
For practical evidence-preservation steps after any serious collision, see After the Crash: A Roadmap for Safety, Evidence, Medical Care, and Insurance Claims.
What This Means in a Real Multi-Defendant Case
The central lesson is that ‘who caused the crash?’ is only the beginning. A plaintiff’s percentage affects whether and how much the plaintiff can recover. Among defendants, the 25% threshold can affect joint liability for nonmedical damages. Medical expenses follow their own rule. Settlements and contribution rights can further change the financial picture.
That makes careful party identification and evidence preservation especially important early in a multi-vehicle case. Missing a potentially responsible party, losing video, or assuming that every defendant will simply pay its percentage can distort the analysis before the case is fully developed.
Frequently Asked Questions
Can I recover in Illinois if I was 50% at fault for a crash?
Generally, yes. Under 735 ILCS 5/2-1116, recovery is barred when the plaintiff’s fault is more than 50%. If the plaintiff is exactly 50% at fault, the award is generally reduced by 50%.
What does the 25% rule mean in an Illinois car accident case?
Under 735 ILCS 5/2-1117, a liable defendant who is less than 25% at fault is generally severally liable for nonmedical damages, while a defendant at 25% or more is jointly and severally liable for those damages.
Are medical bills subject to the same 25% rule?
No. Section 2-1117 provides that defendants found liable are jointly and severally liable for the plaintiff’s past and future medical and medically related expenses.
Does the plaintiff’s employer count toward the 25% calculation?
The statute expressly excludes the plaintiff’s employer from the total fault used for this particular 25% joint-liability calculation.
What happens if one defendant settles before trial?
Illinois’s Joint Tortfeasor Contribution Act can affect contribution rights and the remaining case. A good-faith settlement can discharge the settling tortfeasor from contribution liability, so partial settlements should be evaluated in the context of all defendants and claimed damages.
How long do I have to file an Illinois car-accident injury lawsuit?
Illinois generally provides a two-year limitations period for personal-injury actions under 735 ILCS 5/13-202, although exceptions and shorter deadlines can apply in particular cases.
Disclaimer
This article provides general information about Illinois negligence, joint liability, contribution, and car-accident claims. It is not legal advice and does not create an attorney-client relationship. Fault allocation, damages, insurance coverage, contribution rights, and filing deadlines depend on the facts and parties in a specific case. Statutes and case law can change, and readers should consult a qualified Illinois attorney about an individual claim.
Authorities & Sources
- Illinois General Assembly – 735 ILCS 5/2-1116, Limitation on Recovery in Tort Actions
- Illinois General Assembly – 735 ILCS 5/2-1117, Joint Liability
- Illinois General Assembly – 735 ILCS 5/13-202, Personal Injury Limitations Period
- Illinois General Assembly – Joint Tortfeasor Contribution Act, 740 ILCS 100
- Illinois Courts – McNiff v. Mazda Motor of America, Inc. (2026), discussion of good-faith settlements under the Contribution Act
