6.4 Part C Uninsured/Underinsured Motorists

Purpose of Part C

Part C - Uninsured Motorists (UM) Coverage pays a covered person for bodily injury (and in some states property damage) caused by an uninsured or hit-and-run driver who is legally liable. The coverage steps into the shoes of the at-fault driver who had no insurance, so the insured's own insurer pays what the negligent stranger should have paid. It is first-party coverage that responds only when someone else is at fault.

Three triggering driver categories:

UM vs. UIM

Uninsured Motorists (UM) applies when the other driver has zero liability coverage. Underinsured Motorists (UIM) applies when the other driver has coverage but not enough. Many states require UM be offered; UIM is often a separate add-on. UM/UIM generally covers BI only unless the state adds UMPD (uninsured motorist property damage), which may carry its own deductible.

Worked example - UIM (limits-trigger / difference-of-limits state). Your UIM limit is $100,000. You suffer $120,000 in proven BI. The at-fault driver carries $50,000 liability.

You recover $100,000 (your UIM limit). The remaining $20,000 of damages is unrecovered. In some states UIM instead pays the gap up to your damages but never more than your UIM limit; know your state's rule.

Provisions and Traps

• Rejection in writing. UM/UIM must usually be offered and can be rejected only in writing by the named insured. Absent a signed rejection, the coverage attaches at limits equal to the liability limits.
• Hit-and-run proof. For a phantom/hit-and-run vehicle, many states require physical contact or independent corroboration to prevent fraudulent "phantom car" claims.
• Arbitration. Disputes over whether the insured is legally entitled to recover, or the amount, are typically resolved by arbitration under Part C.
• Stacking. Some states allow stacking - adding the UM limits of multiple owned autos together; others prohibit it via an anti-stacking clause.

Trap - the "underinsured" gap. UIM does not apply just because the other driver's limits are low; it applies only when the other driver's limits are lower than your UIM limit (in a difference-of-limits state) or lower than your damages (in a difference-of-damages state). If your own UIM limit equals or is below the at-fault driver's limit, UIM pays nothing.

UM vs. UIM and the Coverage Gap

Part C splits into two related coverages the exam contrasts:

• Uninsured Motorists (UM) responds when the at-fault driver has no liability insurance, is unidentified (hit-and-run), or the insurer is insolvent.
• Underinsured Motorists (UIM) responds when the at-fault driver has insurance but limits too low to cover the injury; UIM pays the difference up to the insured's UIM limit.

Worked UIM Calculation

An insured with $100,000 UIM is injured for $130,000 by a driver carrying only $50,000 bodily injury liability. The at-fault policy pays $50,000. Under a typical limits-difference state, UIM pays the gap between the insured's $100,000 UIM limit and the $50,000 already collected = $50,000, leaving the insured $30,000 short. Some states instead reduce UIM by the amount recovered; knowing the state offset rule changes the answer, which is why the exam states the method.

What UM Covers and What It Does Not

Why Part C Is Mandatory in Many States

Because a large share of drivers are uninsured or carry minimum limits, UM/UIM protects the responsible insured from the irresponsible motorist. Many states, including Illinois, make UM mandatory and UIM available or mandatory at limits matching the insured's liability unless rejected in writing. The exam frames UM/UIM as the coverage that makes the insured's own policy pay for the other driver's failure to insure — a first-party fix for a third-party shortfall.

Rejection, Stacking, and the Phantom Vehicle

State rules shape three frequently tested UM features:

• Written rejection — because UM/UIM is mandatory or must be offered at liability limits, an insured can usually reduce or reject it only by a signed written waiver; absent that waiver, coverage applies at the higher limit by default.
• Stacking — some states let an insured stack (add together) UM limits across multiple owned, separately premiumed autos; others prohibit it by an anti-stacking clause.
• Phantom (hit-and-run) vehicle — UM covers an unidentified driver, but states often require physical contact or corroborating evidence to deter fraudulent "phantom car" claims.

Recognizing that UM/UIM defaults on unless validly rejected, and that stacking and phantom-vehicle proof turn on state law, accounts for most of the harder Part C exam items.