In Maryland blacked out headlights and blacked out tail lights are illegal and for good reason.
Your headlights are meant to help you see and to help other vehicles see you oncoming in traffic and your tail lights are meant to allow other vehicles to see you when they are behind you at night.
So even if the blacked out headlights and blacked out tail lights were not illegal in Maryland or anywhere else it's a stupid idea to black them out anyway.
Your head lights are supposed to help you see when driving in the dark and your tail lights are there for safety so other vehicles can see you so they don't crash into you.
So you can expect to get a fix it ticket or a ticket in Maryland or most other places for blacked out tail lights.
A blacked out tail lights or blacked out head lights are likely okay for show cars that don't go driving down the road at night.
But if you're driving the vehicle at night then the tail lights need to be clearly seen in red and the head lights need to shine bright enough so you can see other cars, pedestrians, and be able to see where you're going and allow other vehicles and people to see your vehicle.