Liberal politicians who run states and cities have certain habits they come back to again and again. One is the passage of gun bans they know perfectly well are clear violations of the Second Amendment. Why do the do this? Partly because ideologically they can't help themselves. But also: They hope to create test cases in the courts that, they hope, will produce favorable rulings and thus establish case law that renders the entire Second Amendment null and void.
Toward that end, the State of Maryland scored a very big victory today, as the Fourth Circuit Court of Appeals upheld an "assault weapons" ban that can't possibly be defended as constitutional. So why did it survive? Because there are many in the federal judiciary who share the goal of repealing the Second Amendment, and hope to be the judges assigned to these test cases. The Fourth Circuit really outdid itself with this one.