Michigan is the latest state to enact regulations governing autonomous vehicles (AVs), joining California, Nevada, and Florida in codifying the use of advanced technologies that proponents say could vastly improve the safety and efficiency of the U.S. highway system.

Approved by Michigan’s legislature in early December and subsequently signed by Gov. Rick Snyder (R), the regulations permit AV test drives by manufacturers and “upfitters,” provided that a human is literally and figuratively in the driver’s seat to operations and assume control if needed. A companion regulation protects original manufacturers from civil liability for damages caused by third-party party conversions of standard vehicles into AVs.

The research-oriented regulations differ from those of other states, in that they explicitly prohibit non-test uses of AVs on Michigan roads. The restriction has been criticized by Google, which has been fast-forwarding the integration of self-driving technologies into stock vehicles such as the Toyota Prius. Michigan State Senator Mike Kowall (R), the sponsor of the AV test legislation, has promised to work on a new bill broadening the use of AVs.

As for the other 46 states and U.S. territories, AV proponents have argued that the absence of any explicit regulations makes the use of these vehicles legal under any conditions. (A state court might see things differently should a crash or other incident involving an AV occur.)

Michigan’s AV law arrives just two weeks after Ford debuted its automated Fusion Hybrid research vehicle. Developed in a collaboration with University of Michigan robotics and automation specialists, and State Farm Insurance Company, the vehicle will test current and future sensing systems and driver-assist technologies, with an eye toward integrating these features in Ford’s vehicles as early as 2025.

According to Ford’s announcement, researchers will augment the Fusion’s existing driver support technologies (e.g., Blind Spot Information System, active park assist, lane-departure warning, and adaptive cruise control and collision warning) with four Light Detection And Ranging (LiDAR) sensors capability of scanning its surroundings 2.5 million times per second, with the analytical capability to recognize stationary and moving objects, and discerning between a paper bag and a small animal as much as 300 yards away.

Ford is also working on vehicle-to-vehicle communication technologies to provide drivers with more timely information regarding upcoming traffic, infrastructure, and weather conditions.

Just how soon AVs have on infrastructure design and operation implications remains to be seen. Research presented at the Eno Center for Transportation this fall noted that implementation barriers such as vehicle affordability, insurance and liability, and owner privacy could limit AVs to being little more than novelties well into the middle of the century.

Still, it’s never too early to start planning for the advent of AVs. As one of the “hot topics” of January’s Transportation Research Board Annual Meeting, automated vehicles figure prominently in 15 workshops and sessions looking at current technology research, planning and operational implications, and effects on other transportation modes.