That’s the only kind of insurance coverage that Washington state requires that you purchase. That’s automobile insurance that you pay for that will protect someone else, if you cause them harm. Everyone is supposed to have Washington liability insurance, not everyone does. You need to buy UIM insurance which steps into the shoes of that, if someone else doesn’t have it. The minimum amount in Washington for liability insurance is $25,000, but please purchase more. It will protect you, as well as others.