There are different kinds of folding knives like pocket knives, gravity [inertia] knives and switchblades. The kind of knife that Freddie Gray had is an assisted opening knife, according to its description in the police report ("Freddie Gray's knife could be key factor as charges challenged," May 9). The knife has a spring opening mechanism that is activated by pushing against a knob on the side of the blade which activates a spring mechanism that fully opens the blade. A switchblade, on the other hand, is fully automatic. You depress a button in the handle and this activates a spring mechanism that fully opens the blade by propelling it forward or swinging open. It is considered automatic because you do not touch the blade, only the handle. What both kinds of knives have in common is that they are opened either fully or partially by a spring mechanism.
By contrast, a plain pocket knife is opened manually by grasping the blade with your fingers and pulling it open. There are no springs or other devices for assisting the opening of the blade. It is entirely manual. Depending on the particular codes of the venue, these kinds of knives are generally legal.
Switchblades and assisted opening knives are similar to each other but structurally and functionally different from pocket knives that are opened manually. Baltimore Code 19.59.22 specifies that a knife with an automatic spring or other device for completely or partially opening the blade is illegal. For assisted opening knives, the "other device" is the spring-loaded mechanism that assists the blade in opening. A pocket knife that opens manually would be legal but the switchblade and assisted opening knives are illegal in Baltimore.
One of the reasons that assisted opening knives are generally illegal is because they are so similar and both can be opened rapidly with the flick of a finger. With a switchblade, you press a button in the handle and with an assisted opening knife you press a little knob on the side of the blade. For both knives, the blade springs open by the action of the spring mechanism. It is the action of the spring mechanism that propels the blade.
Gary J. Kaplowitz, Pikesville