Auto insurance is a contract that protects your financial security in case of an accident. Although it is not mandated by federal law, the purchase of auto insurance is usually a requirement in most states; every state (with the exception of New Hampshire and Wisconsin) have minimum insurance laws.
These two states, instead of having insurance requirements, have mandated financial responsibility laws, so that the owner of a car is required to show that he has sufficient funds to pay any necessary claims. If said owner cannot produce proof of satisfactory assets, then he must buy an auto insurance policy. Regardless of the law, having good auto insurance is practical for the driver who wishes to avoid lawsuits or immense repair bills.