Here is the current statute:
http://mlis.state.md.us/asp/statutes_respond.asp?article=gcr§ion=4-101&Extension=HTML
I'm going to paste a response I gave to this same query previously:
The law doesn't clearly state they're illegal to carry, nor does it clearly state they're legal.
I know legalese gives people fits, so I will sum up as best I can in lay terms.
1. Maryland has absolutely no restrictions on the private ownership batons. Indeed, they have no restrictions on ownership of most non-firearm weapons. It's even legal to own a switchblade.
2. Title 4-101 only makes it illegal to carry particular weapons concealed or openly with intent to unlawfully injure (i.e. brandishing or threatening another person in a non-self-defense situation). Open carry of batons is legal. When I was a guard, I carried an ASP on my belt. I had no certs or permits, but LEOs would come by everyday to chat or haul away people we detained, and never said anything.
3. In Title 4-101, there is a list of weapons provided, but none of them are baton-like. This means a baton is not a "per se" weapon (not explicitly named in law). There is a vague "dangerous weapon" that may be be applied to any purpose made weapon, but several officers have told me that because it is not a "per se" weapon, the court must prove intent to commit a crime for a CDW charge to stick.
4. 4-101 contains a defense to raise in court against a CDW charge: "an individual who carries the weapon as a reasonable precaution against apprehended danger" is not in violation of this statute. This is a defense against a charge, not a free pass to avoid arrest.
Currently, I live in MD and occasionally carry a 16.75" Monadnock Autolock (they're heavier than ASPs and close with a button) or an ASP Agent (in summer). It is a calculated risk I take because I have never encountered a case where a person was arrested, much less convicted, for no other reason than they were carrying a baton. But, there is no guarantee a LEO I meet is going to be as well versed in the law as I am. There are several prominent cases of arrests that result in nolle prosequi (case dismissed without trial).
So the choice to carry is up to you. Could you be arrested? It's possible, assuming you do something to attract police attention in the first place. In 10 years it has yet to happen to me. Would you be convicted? Not very likely, but not impossible either.
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Now, if you bring it to college, that is another matter. Colleges have their own policies, and only you student handbook or you campus police can tell you if it's permitted to have something like this on campus. If you ask the campus PD though, make them cough it up in writing. Too many times you ask police this kind of thing you get a flat "not allowed" with out anything to back that up other than the officer's personal opinion.
I also concur wholeheartedly with HSO's comment: Cheap junk is a liability. If you paid under $40 for it, you just bought a cheap novelty that will break or get jammed after 2 or 3 hits.