In the United States, some states have enacted legislation making medical marijuana legal -- despite it being illegal at a federal level. This situation presents privacy issues for both retailers and patients.
In her "Data Security And Privacy" podcast series, privacy consultant Rebecca Harold (@PrivacyProf) interviewed a patient cannabis advocate about privacy and data security issues:
"Most people assume that their data is safe in cannabis stores & medical cannabis dispensaries. Or they believe if they pay in cash there will be no record of their cannabis purchase. Those are incorrect beliefs. How do dispensaries secure & share data? Who WANTS that data? What security is needed? Some in government, law enforcement & employers want data about state legal marijuana and medical cannabis purchases. Michelle Dumay, Cannabis Patient Advocate, helps cannabis dispensaries & stores to secure their customers’ & patients’ data & privacy. Michelle learned through experience getting treatment for her daughter that most medical cannabis dispensaries are not compliant with laws governing the security and privacy of patient data... In this episode, we discuss information security & privacy practices of cannabis shops, risks & what needs to be done when it comes to securing data and understanding privacy laws."
Many consumers know that the Health Insurance Portability and Accountability Act (HIPAA) governs how patients' privacy is protected and the businesses which must comply with that law.
Poor data security (e.g., data breaches, unauthorized recording of patients inside or outside of dispensaries) can result in the misuse of patients' personal and medical information by bad actors and others. Downstream consequences can be negative, such as employers using the data to decline job applications.
After listening to the episode, it seems reasonable for consumers to assume that traditional information industry players (e.g., credit reporting agencies, advertisers, data brokers, law enforcement, government intelligence agencies, etc.) all want marijuana purchase data. Note the use of "consumers," and not only "patients," since about 10 states have legalized recreational marijuana.