Self-driving autonomous vehicles (AVs) have the potential to make the world a safer and cleaner place. A challenge confronting the development of AVs is how these vehicles should behave in traffic situations where harm is unavoidable. It is important that AVs behave in ethically appropriate ways to mitigate harm. Ideally, they should obey a system of principles that both concur with human moral judgments and are ethically defensible. Here we compare people’s moral judgments of AV programming with their judgments about the behavior of human drivers, with the goal of beginning to identify such principles. As many debates within ethics remain unresolved, empirical investigations like ours may guide the development of ethical AVs (Bonnefon et al., 2015). In addition, people’s judgments about the behavior of AVs may serve as a window into the abstract principles people apply in their moral reasoning.