Uninsured / Underinsured Motorist Insurance coverage is the most important coverage you can have. In California, it has been estimated that 1 in 4 motorists are driving uninsured (UM) or underinsured (UIM), that is without adequate liability insurance protection. What this means is that they either have no insurance or not enough to cover any responsibility they have as a negligent driver who injures others. When you suffer personal injuries from an UM/UIM, even when you are not driving, you will be covered for the full extent of your injuries up to your policy maximum. To make sure you are covered, you should purchase uninsured/ underinsured motorist coverage in the highest amounts you can reasonably afford.