I figured I'd share this, since it comes up all the time on the main forums.
I called the State Police barracks in my area a while back about this. They directed me to the MVA's code department in Glen Burnie, so that's who I got this information from. Apparently, I was the FIRST person to ever call about this law, as it would seem nobody has thought to do so before, lol.
Doors off is 100% legal. The exact words were "While I don't recommend riding doorless, there is NO LAW that states you cannot ride doorless in a Jeep." So I brought up a possible interpretation by individual officers. He said that while that may be open to the interpretation of the officer, there is no code he can cite you for violating. Ocean City cops are notorious for ticketing doorless Jeeps, because the driver's don't have the knowledge of the laws. Knowing the law and how to defend yourself to the officer is paramount. If you do get pulled over, tell the officer to quote you the law stating it's illegal to ride doorless in a vehicle designed to have removable doors. He can't get you for a safety violation either, because the Jeep's doors are not safety equipment. Tell them you talked to the MVA's code division, and that the officer should call to confirm as well. If they can't quote a specific violation, they can't legally cite you for an equipment violation. Also, local codes CAN NOT override state codes, which I've heard has been one they've tried to pull as well. But for God's sake, wear your seatbelt and follow the law, you'll be asking for attention from some of the more picky officers riding without doors.
You are REQUIRED to have a rearview mirror, and a driver's side mirror that provides a view of at least 200 feet to the rear of the vehicle. I told the guy I talked to that I planned to use a stick-on wide angle mirror, placed on my driver's side vent that I could rotate around to use when I'm doorless, and he said that so long as it provides the required rearward view, I MOST LIKELY won't get bothered, but the mirror SHOULD be on the outside of the vehicle. He said since the mirrors are on the doors, and the doors are legally removable, as long as you have SOMETHING, you SHOULD be fine. To this date, I have yet to get stopped.
Now, understand that what I've posted applies to Maryland, and Maryland alone. I can't speak to the laws and codes other states, even if they are similar. If you're not willing to believe some guy on the internet, by all means, call them for yourself, I won't be offended.