While marijuana is legal in several states, some people may still be wary of purchasing cannabis since it's still illegal at the federal level. They worry that the feds will target them for buying a "illegal drug." But is there actually any reason to worry?
Politifact recently investigated how marijuana businesses handle customer information. Under most state laws, dispensaries are only required to check a person's ID before allowing them purchase cannabis. There's no law requiring them to retain customer information for the future. However, there's also no law that says they can't retain that information, so some dispensaries will scan driver's licenses or give out contact forms to customers. Neither of those acts would but a customer in danger, but if someone was worried about giving out private information, they can always refuse or visit another dispensary.
The larger issues for privacy are videotaping and delivery. Most states require dispensaries to have surveillance cameras in place that record customers. Again, this wouldn't normally be an issue, but privacy concerns are more typical when it comes to cannabis. And most companies that deliver marijuana also keep those orders on record as well.
However, despite all this data, most experts says that privacy concerns are pretty minimal for customers. The federal government, if it were to begin a crackdown, would focus more on the cannabis businesses themselves rather than the people buying the products. Even the DOJ wouldn't be stupid enough to arrest people for buying something that's legal under state law.
But then again, Jeff Sessions is in charge of the DOJ, so who knows.