Fully-automated driverless vehicles will likely drastically change the way people and goods are transported, implicating land use and transportation. They would not only provide a convenient means of transportation to many, but also become an effective tool to reduce transportation-related greenhouse gas (GHG) emissions, which account for a large portion of the total emissions in many jurisdictions throughout the world. To encourage the use of fully-automated driverless vehicles as such a tool, this article proposes several legal mechanisms that should be adopted in California. Although these legal mechanisms have been developed based primarily on existing California laws, countries and jurisdictions throughout the globe that wish to efficiently minimise transportation-related emissions should consider adopting these legal mechanisms because they can readily be adopted in various jurisdictions including those currently lacking a legal framework similar to California’s. This article proposes these legal mechanisms primarily by examining existing California laws intended to reduce the transportation-sector emissions, including the California Global Warming Solutions Act of 2006, or Assembly Bill 32, and the Sustainable Communities and Climate Protection Act of 2008, or Senate Bill 375, and the potential impacts that driverless vehicles would have on GHG emissions based on expert opinions and literature review. The legal mechanisms proposed in this article would serve as foundations on which a more comprehensive scheme of GHG emissions reduction measures related to fully-automated driverless vehicles can be developed as driverless vehicle technology further develops.