However, Baltimore City (and some other places) have a complete ban on carry for self defense (including long guns). To my knowledge, no one has ever sued Baltimore City, but that would be an interesting test case.
Baltimore City does have a complete ban on long gun carry. However... see page 172 on:
http://ca.baltimorecity.gov/codes/Art 19 - PoliceOrds.pdf
There is an exception for permit holders in regard to where one can carry.