For the first time, in March, an autonomous car drove itself from San Francisco to New York City. How is that even legal? That’s the kind of question Bryant Walker Smith, an assistant professor of law at the University of South Carolina, tries to answer. He’s an expert on the legal implications of self-driving cars. Smith sees a future in which these vehicles all but eliminate crashes, transform liability, and make us look back in horror at the risks we once took on the road.