After a car accident in Illinois, legally your case is nominally against the at-fault driver, or "tortfeasor." But in reality, it is against his insurance carrier.
Thus, it is absolutely essential that YOU HAVE THE MOST INSURANCE COVERAGE POSSIBLE. Why? Because in Illinois, the minimum auto insurance coverage is $25,000 per person per incident and $50,000 per incident total. Many drivers have only this minimal coverage, which is almost never enough to pay medical bills and other losses after a serious car accident.
Based on the minimum auto policy coverage amounts in Illinois, if you are struck from behind by a minimally insured driver, sustain a serious back injury, undergo surgery, and cannot work for 4 months, you may be limited to a mere $25,000 in recovery unless your insurance has higher levels of coverage for liability and underinsured motorist coverage (UIM).
By the same token, if the other driver had no insurance, had expired insurance, or had insurance that wouldn't cover this incident (say he was driving for commercial purposes or was using a car that wasn't on the policy and which he was not permitted to drive), you would be completely out of luck unless you had good insurance coverage that contained uninsured motorist coverage (UM).
All auto policies in Illinois will have coverage limits for Uninsured (UM) and Underinsured (UIM) that are at least equal to the limits on your liability policy. Thus, if you have a policy with $250,000 per person liability and $500,000 per incident, you would have those figures to recover as your upper limit if you were involved in a collision with an underinsured or uninsured person.
How does this work? Using the example from before, you are involved in the serious crash with the driver who has the minimal policy of $25,000. It is a safe bet that you will be able to recover the policy limits from the other driver (assuming he is at fault and you had a lawyer representing you). But now, instead of only being able to recover $25,000, you could have as much as $250,000 plus $25,000 ($225,000) to recover for your medical damages, future medical damages, pain and suffering, loss of a normal life, and lost wages.
If you were involved in the same crash with an uninsured driver, your claim would be against your own insurance carrier for up to the full $250,000 policy.
Insurance is confusing, so make sure you really know what you are purchasing. Don't just buy whatever is cheapest or whoever's commercials you like best. Research the companies online and look at their ratings for paying claims, customer satisfaction, and insurance industry ratings.
Some other things to make sure you have in the event you are involved in a car crash:
Other things to be sure of before it is too late is whether your use of the insured vehicle is covered. For example, if you travel for work as a salesperson, is that covered under your auto policy, or is it considered commercial use, which is not covered by most policies? Does your Medical Payments Coverage (PIP) cover you if you are involved in a crash that is out of state?
One more thing to worry about. Most health insurance carriers exclude paying for medical treatment that is a result of a third party's fault (i.e. a car crash). If you incur bills due to being injured in a car crash, that makes it really important that you have a high limit of Medical Payments (PIP) coverage. Otherwise, you could wind up holding the bag for medical bills that your health insurer won't pay.