We asked a few experts if any of this is legal. And the general consensus was ¯_(ツ)_/¯. The truth is, none of this is clear, for a few reasons. First, it remains to be seen exactly what Tesla plans to offer. Musk says the feature will be restricted to highway use (follows the trajectory of automakers like Mercedes-Benz and Audi), but did not specify its capabilities. When Tesla first mentioned autonomous features in October, it said “Model S will be able to steer to stay within a lane, change lanes with the simple tap of a turn signal, and manage speed by reading road signs and using active, traffic aware cruise control.” We don’t know if that’s still the plan, and no one at Tesla returned our call seeking clarification. But on Thursday, Musk said, “there’s certainly an expectation that when autopilot on the Model S is enabled, that you’re paying attention.”

Adding to the uncertainty, the rules regulating self-driving cars are a mess. Only California, Nevada, Michigan, Florida, and Washington, D.C. govern how the vehicles can be tested. Those laws largely apply to testing, so the legality of taking a car straight to market there may be flexible: Nevada requires a special license and registration, but that only applies to cars sold in the state. Florida basically legalized it, saying it “does not prohibit or specifically regulate the testing or operation of autonomous technology.” In California, the technology can only be tested, and is not allowed for consumer use until further notice. According to Stanford Law School’s Center for Internet and Society, 14 more states are working on regulations, and a dozen have voted them down.

This is good news for Tesla. Because this is America, whatever’s not illegal is legal. Aside from those states (and Washington DC) that have regulated autonomous vehicles, and New York (which requires drivers keep at least one hand on the wheel at all times) there’s no law against Tesla flipping a switch making it possible for the Model S to chauffeur itself down the highway. That leaves 45 states of freedom, and maybe New York, if you’re super literal and keep a hand on the wheel without actually doing anything.

...There are no federal regulations in place yet, but based on a 2013 non-binding statement, NHTSA isn’t hot on the idea of consumer operation of autonomous vehicles just yet. It “could also attempt to intervene if it has evidence that automated vehicles are not reasonably safe,” Smith says...But if the software lets the Model S operate like a Level 3 car, letting the human “cede control of all safety-critical functions” to a machine that can, say, change lanes on its own, then it’s illegal. Cars with such capabilities, like the Audi A7 I piloted from Silicon Valley to Las Vegas, must be certified as test vehicles before they hit the pavement. You can’t sell them to the public.

...California, for its part, is hardly anti-autonomous driving. It created its rules as a framework for the testing a whole slew of companies were already doing in Silicon Valley, and already is working on rules for allowing Level 3 cars on the market. “We’re smack dab in the middle of them now,” says Bernard Soriano, deputy director at the state’s DMV. He would not offer an ETA, but says “we’re close.” That process includes the automakers, Soriano says. “We’ve been working very collaboratively with them and to their credit, they’ve been very open with us.”

--"Elon Wants to Make Your Tesla Drive Itself. Is That Legal?"