In California, self-driving cars are street legal. Florida, and Nevada allow for self-driving autos to be tested on their roads, and Michigan may soon join the club. But so far, the 46 other states in the US have steered clear of automated automobiles — something the Department of Transportation's National Highway Traffic Safety Administration (NHTSA) hopes to change. On Thursday, NHTSA released a policy report calling on states to draft legislation that allows for the testing of self-driving cars.

The policy report urges states to not only allow for the testing of self-driving experimental cars — the likes of which are being tested by Google, Mercedes-Benz, Nissan, and others — but also offers up suggestions on what sort of laws to pass "to ensure that their legislation does not inadvertently impact current vehicle technology and that the testing of self-driving vehicles is conducted safely," NHTSA said in a statement. The report also outlines five levels of automation that the agency classifies self-driving cars within.

The categories run from "No-Automation (Level 0)," which features no automation technology and relies on a driver for every function (steering, accelerating, breaking, etc.), to "Full Self-Driving Automation (Level 4)" in which a vehicle is "designed to perform all safety-critical driving functions and monitor roadway conditions for an entire trip." Level 4 cars are built to rely on a driver only for "destination or navigation input," but not necessarily any driving control during a trip. "This includes both occupied and unoccupied vehicles," NHTSA said, acknowledging not only self-driving cars, but also driverless autos too.