Mass-diver
NES Member
Although I have not verified the cases he cites, the author does provide examples of persons prosecuted for "gun in the commission of a drug crime" for MJ users.
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What about the grow/package places?
These places are obviously, much, much easier to defend than retail operations. You basically just have a couple layers of key card access, cameras, and good door. Plus, it's a secret when harvest time is....