Baltimore considers “switchblades” to be illegal.
Gray had a regular folding knife, which is legal (unless concealed). Gray had his knife attached to his belt (not concealed), and the police improperly called it a switchblade.
It was an illegal arrest.
The convict was LEGALLY arrested, for cause. No, it was not a true switchblade, but he was carrying a spring-assisted knife BANNED BY BALTIMORE CITY CODE. Maryland does NOT have a state-level knife law preemption law.