According to the Department of Motor Vehicles, how much liability insurance is required depends on the state in which you live. Most states have a minimum limit that drivers must have, but some states do not require any liability insurance at all.
The minimum amount of liability coverage you must carry is the maximum amount your insurance pays out in the event of an accident. Even if you are not required to carry liability insurance, the DMV recommends carrying it anyway. Choosing not to carry it can result in such consequences as being sued for damages or medical costs by the other party in an accident.