In November, I noted in The Washington Post and here on Open Market that a bill introduced in the D.C. Council contained two dangerously flawed provisions and another unnecessary and overcautious provision. Basically, the original bill 1) nonsensically mandated that autonomous vehicles operate using alternative fuels, 2) established a special tax that would further reduce consumer purchases, and 3) required that a licensed driver be in the driver's seat of the vehicle during autonomous operation, which is unnecessary and will restrict potential testing and functionality (admittedly, this is far less severe than the first two).
D.C. will soon join Nevada, Florida, and California as jurisdictions that have explicitly legalized autonomous vehicles. There are few laws and regulations that explicitly ban the operation of autonomous vehicles in the United States, making them technically legal virtually everywhere provided a licensed driver is in the driver's seat. But these legalization efforts are important to both send a positive signal to potential developers and establish a framework to address public policy and legal issues that will arise as consumers begin to adopt autonomous vehicles. Bryant Walker Smith, perhaps the foremost expert on the law as it relates to autonomous vehicles, recently authored a fascinating paper that explores these issues in great detail. For those who want a brief overview, see Smith's article in New Scientist.