Chicago Uninsured Motorist Lawyer — when their policy is empty, your policy pays.

Uninsured motorist and underinsured motorist coverage are not the same thing.

Illinois auto policies often pair these coverages, but they apply to two distinct fact patterns. Knowing which one applies to your crash determines how the claim is filed, what limits are available, and what the carrier will argue.

UM (Uninsured Motorist) under 215 ILCS 5/143a

UM applies when the at-fault driver:

• Has no insurance at all at the time of the crash.
• Cannot be identified — hit and run where the driver fled and cannot be located.
• Is operating a stolen vehicle with no policy that responds.
• Has a policy that has been canceled, denied, or is otherwise unavailable to respond.

UM coverage in Illinois is mandatory. Every auto policy issued in this state must include UM at minimum $25,000 per person and $50,000 per accident.

UIM (Underinsured Motorist) under 215 ILCS 5/143a-2

UIM applies when the at-fault driver has insurance, but the policy limits are insufficient to cover your damages. Example: the at-fault driver carries the Illinois minimum $25,000 liability policy, you have $250,000 in damages, and you carry $100,000 UIM limits — your UIM coverage pays the difference between the at-fault policy and your UIM limit.

UIM is required in Illinois at minimum limits matching UM, but the policyholder can reject UIM in writing or reduce it to lower limits. Without a written rejection, the carrier must provide UIM coverage equal to the policyholder's bodily injury liability limits.

When and how UM/UIM limits stack in Illinois.

"Stacking" means combining the UM/UIM coverage from multiple vehicles on the same policy, or from multiple policies in the same household, to create a higher total recovery. Illinois law on stacking is governed by both statute and case law, and policy language varies. Whether you can stack often determines the difference between $25,000 in available coverage and $100,000 or more.

Inter-policy stacking

Inter-policy stacking combines UM/UIM coverage from separate policies — your policy plus a resident relative's policy plus a household member's employer-issued auto policy. Illinois courts have generally allowed inter-policy stacking unless the policy contains a clearly drafted anti-stacking clause that comports with the Illinois Insurance Code and case law. The fight is almost always about whether the policy language is clear enough to defeat stacking.

Intra-policy stacking

Intra-policy stacking combines UM/UIM coverage across multiple vehicles listed on the same policy. If your policy covers three vehicles each with $100,000 UM/UIM limits, intra-policy stacking would create $300,000 in available coverage. Illinois courts have generally allowed intra-policy stacking unless defeated by clear anti-stacking language in the policy.

Household policies and resident-relative coverage

UM/UIM coverage typically extends to resident relatives of the named insured — spouses, children, and other family members living in the same household. A child injured as a pedestrian or cyclist may be covered under a parent's auto policy even though the child has no policy of their own. A spouse injured in another person's vehicle may be covered under both that vehicle's policy and the spouse's own household policy. Identifying every potentially applicable policy is one of the first investigative steps in any serious crash case.

UM/UIM arbitration — what to expect.

Nearly every Illinois UM/UIM policy contains an arbitration clause requiring binding arbitration when the parties cannot agree on (1) whether the policyholder is legally entitled to recover or (2) the amount of damages. Unlike civil litigation, arbitration takes place in a private hearing, before an arbitrator (usually a retired judge or experienced attorney), without a jury, and with limited appellate review.

How UM/UIM arbitration works

1. Demand for arbitration. The claimant serves a written demand on the insurance carrier identifying the disputed issues. Most policies require this demand within the two-year statute of limitations period.
2. Arbitrator selection. Most Illinois UM/UIM policies use a three-arbitrator panel (one selected by each party, the third selected by the first two) or a single neutral arbitrator selected by mutual agreement.
3. Discovery. Limited discovery is typically allowed — medical records, deposition of the claimant, sometimes deposition of treating physicians. Discovery is shorter and tighter than civil litigation discovery.
4. Pre-arbitration motions. Motions in limine, disputes over the admissibility of evidence, and pre-hearing rulings on legal issues happen before the hearing itself.
5. Arbitration hearing. Each side presents opening statements, witnesses, exhibits, and closing arguments. Treating physicians may testify in person or by deposition. The hearing typically lasts one to three days.
6. Award. The arbitrator issues a written award stating the amount of damages, typically within 30 to 60 days of the hearing. The award is binding subject to limited grounds for appeal.

Why arbitration is not a quick win

The carrier's arbitration counsel handles UM/UIM cases full-time. They know the arbitrators, the medical defense experts, and the strategies that limit recovery. An effective UM/UIM presentation requires the same case-building discipline as a jury trial: clean medical records, organized billing summaries, treating physician testimony or deposition, economic loss documentation, and a coherent damages narrative. Half-prepared arbitration presentations result in undervalued awards.

When the carrier crosses the line.

UM/UIM carriers are legally obligated to handle claims in good faith. When a carrier delays without justification, denies coverage in the face of clear evidence, refuses to engage in good-faith settlement negotiation, or otherwise acts vexatiously, Illinois law provides a remedy under Section 155 of the Illinois Insurance Code (215 ILCS 5/155).

What 215 ILCS 5/155 provides

If the court finds that the carrier's conduct in connection with the claim was "vexatious and unreasonable," the court can award:

• Attorney's fees incurred in pursuing the claim.
• Costs of the litigation.
• An additional penalty of up to 60% of the amount the policyholder is entitled to recover, or $60,000, whichever is less.

What is "vexatious and unreasonable"

Illinois case law has identified vexatious conduct in cases where the carrier denied a clearly valid claim, took inconsistent positions, refused to investigate before denying, ignored the policyholder's medical evidence, or used dilatory tactics designed to pressure a low settlement. Honest coverage disputes are not vexatious — but pattern conduct designed to wear the claimant down often is.

What to do to protect your UM/UIM claim.

1. Get medical attention immediately. Same-day medical documentation is the foundation of every UM/UIM claim. Delays of even a few days are exploited by carriers to argue the injuries were not caused by the crash.
2. Notify your own carrier promptly. UM/UIM policies require prompt notice. Provide the basic facts only. Do not give recorded statements. Do not speculate about fault. Do not minimize injuries.
3. Preserve all evidence. Police report (RD number), photos of the scene and damage, witness contact information, and surveillance footage from nearby businesses. Send preservation letters fast — footage gets overwritten on a rolling cycle.
4. Verify the at-fault driver's coverage carefully. Some "uninsured" drivers actually have coverage that responds — the carrier just has not been notified. Investigation may reveal a policy. The opposite is also true — drivers claiming to have coverage sometimes have policies that were canceled or are non-responsive.
5. Identify every potentially applicable policy. Your policy, resident relatives' policies, household member policies, employer-issued auto policies, rideshare policies if applicable, and any policy under which you might qualify as an insured. Stacking opportunities depend on this inventory.
6. Do not settle the underlying liability claim without considering UIM implications. Settling with the at-fault driver's liability carrier without proper notice to your UIM carrier can destroy the UIM claim. Most UIM policies require pre-settlement notice and consent.
7. Call counsel before you sign anything. UM/UIM claims involve interlocking policies, anti-stacking clauses, exhaustion requirements, set-offs, and consent provisions that defeat unwary claimants. The wrong signature on a release form can extinguish the entire claim.

Chicago UM/UIM questions — answered straight.

Click any question to expand the answer.