If the license plates of a Maryland vehicle are expired, meaning the registration on the vehicle is expired, then it would appear at least one of the citations you would be given is for driving without registration.
Under Maryland Transportation Code section 13-401 it notes under subsection b and c that if a car is not registered in a person may not drive on the highways of this state and that if a vehicle is not registered the owner of the vehicle may not knowingly allow the vehicle to be driven on the highways of this state.
You may have also been written up for unpaid registration fees since that is a separate offense from what we have read. It is noted under subsection d of the Section 13-401 states that if the required registration fee for a vehicle has not been paid, a person may not drive the vehicle on a highway in this State.
And in subsection e it is noted that if the required registration fee for a vehicle has not been paid, the owner of the vehicle may not knowingly allow the vehicle to be driven on a highway in this State.
A person who drives or attempts to drive a vehicle on any highway in this State in violation of any of the registration laws is guilty of a misdemeanor. In MD expired registration plates may not be displayed.
A violation of these provisions is a misdemeanor, subject to a penalty not exceeding $500. From the fine schedules for MD that we have read it appears the fine is typically $280 for driving a car without registration or with expired registration but no points assigned to your driving record.
To find out the exact amount of your fine and what penalties you will face you should contact the court listed on your citation if you have been ticketed for this offense. You may see if renewing your registration and taking in this proof to court can help minimize your penalties.
The Maryland Motor Vehicle Administration (MVA) requires proof of insurance before you renew your registration, so make sure you have valid proof of insurance to show when renewing the vehicle's registration or else you have to pay a hefty uninsured motorist penalty.