Every state has a law that requires drivers on its roads to carry a minimum amount of car insurance. This car insurance, issued by private insurance companies, provides drivers with compensation in the event that they are involved in a car accident and are liable for damages to another party. Policies are usually linked to specific cars. To receive a policy for a car, the policy must be issued in the name of the car's owner.
Generally, a car insurance company will only insure a car in the name of the person who is listed on the car's title. So, for example, if your wife is listed as the car's owner, then an insurance policy for the car would have to be listed in her name. You could not be listed on the policy while your wife is not. However, you two could have a joint policy with both your names.
While the insurance policy has to include your life because she is listed on the car's title, you may or may not have to be listed on the policy. Some insurance companies will require that a spouse who drives his wife's car be listed on the policy. However, if you only drive the car occasionally, you may not need to be listed on the policy. You cannot, however, take out a separate policy on the car.
If your wife already has an insurance policy on the car, you can likely be added to the policy, too. To do this, you should contact your insurance company and ask them what rates they have available to couples. Your premium may go up, particularly if you are considered a higher insurance risk than your wife. For example, if your driving record is bad, your rate will likely rise.
You can also buy a separate policy for yourself, but it can't be linked to the car your wife drives, only to another vehicle. This policy may, however, extend some coverage if you drive other vehicles as well. In some cases, you may be unable to be added to your wife's policy. This would happen if you presented a large enough liability---for example, if you had been convicted of multiple DUIs---that insurance companies did not wish to insure you.