Stun guns (including Tazers) are legal in MD except in Annapolis, Baltimore & Howard County where they are prohibited.
Essentially, in the rural counties, and the rich suburban county of Montgomery (where there is very little crime), Stun Guns are OK in MD, but in the locations where might actually NEED to defend your life against some violent thug, people in the MD General Assembly (like Senator Brian Frosh--who is, BTW, a Partner in the biggest criminal defense law firm in the state...) say you must remain defenseless--even to the exclusion of less-than-lethal options.
It is against the law (according to most MD Court rulings and precedents), however, in ANY location in MD to carry ANY "weapon" concealed without a permit, and the Courts have ruled in MD that stun guns and tazers ARE "dangerous weapons". Although not specifically named in the Statute, there IS court precedent...
http://law.justia.com/codes/maryland...title-1/4-101/§ 4-101. Dangerous weapons.
(1) A person may not wear or carry a dangerous weapon of any kind concealed on or about the person.
If you feel that you may need to defend yourself in MD, the best bet is to move to VA and never "cross the moat".
Barring that, your second alternative is to get a good attorney, and have good medical insurance, and HOPE that when you ARE attacked, you are only injured, and can survive with enough functionality intact to testify against the thug if the police ever get around to apprehending them.
Interestingly enough, if you ARE attacked and survive, then you can put that police report in with your permit application, and it MAY qualify as a 'good and substantial reason"...
Good luck. I've been here 3 weeks, and it's driving me up a wall that I can't carry.
But I would ask that you join me in my "Empty Holster Open Carry" protest that I engage in EVERY TIME I step out of the house. The only time I don't EHOC is when I'm at work. So far, I've had no problems, no issues, and not even a single question or comment from the citizenry. But the more of us who EHOC, the better, because eventully, we will get some attention, and people will start to ask what we are doing.
At which point, we just smile and respond, "I'm carrying my self-defense tool the only legal way I can in MD--leaving it at home, and praying I don't have to dial 911..."