Is a knife with the Emerson Wave feature and a blade exceeding 4" is legal to carry in Michigan?
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I would likely carry this in my pocket (not sure if that counts as "concealed" or not. Obvious use case is a self-defense situation where life is threatened.
MCL 750.226a makes the carrying of "any knife having the appearance of a pocket knife, the blade or blades of which can be opened by the flick of a button, pressure on a handle or other mechanical contrivance" a misdemeanor.
So the question is whether or not a knife with the Emerson Wave feature can be opened by "other mechanical contrivance." There does not appear to be any case law in Michigan interpreting what would be a mechanical contrivance. However, the phrase would be interpreted by reference to the other parts of the statute that refer to pressing a button or putting pressure on the handle. I would argue that the Emerson Wave feature is not similar to a switchblade because it has no springs or other mechanisms that are similar to a classic switchblade. But, the police or a judge might interpret the law differently, so there may be some small risk of being found to have violated the law by carrying it.
I would also note that the length of the blade is not relevant to whether or not a switchblade is illegal to carry.
Finally you need to be aware of MCL 750.226 which makes carrying a weapon with intent to use it unlawfully a felony.