Drones will soon be able to bring a lot of different goods to your house thanks to Amazon and other retailers, but one thing they won't be able to drop on your doorstep is marijuana. Even though the drug has been legalized in California and recreational marijuana sales will be permitted starting on January 1, delivering it using unmanned vehicles like self-driving cars and drones will be banned under a new rule that is quite a buzzkill for some marijuana delivery startups.

According to the Medicinal and Adult Use Cannabis Regulation and Safety Act, "cannabis goods" must be transported in commercial vehicles or trailers. The law specifically lists drones and unmanned vehicles alongside human-powered vehicles, watercraft, aircraft and rail as outlawed methods of delivery.

In addition, the vehicles used to transport it are required to have lock boxes in which it can be secured while being transported and when the truck is left unattended. Moreover, the vehicles cannot be parked anywhere in residential areas or left unattended overnight. The rules apply whether the marijuana is recreational or medicinal.