There was a time when all you needed to call in a prescription in Denmark, was the doctors authorization number... Which was publicly available. Sure if you called in a prescription at a pharmacy across the country or sounded suspicious, the pharmacy would make a call back, but other than that all you had to do was pick a doctor in an area with lots of other doctors and near a large pharmacy, and you'd get whatever you liked.

It must have been so for +10 years before a journalist and a doctor blew it up, by having the journalist phone in prescriptions for morphine, barbiturates, and other recreationally applicable substances. I don't know if a doctor can still phone in prescriptions, but the immediate stop gap was to only accept prescriptions accompanied by the doctor's personal, and crucially private, SSN.