Scientists, engineers and policymakers are all figuring out ways drones can be used better and more smartly, more precise and less damaging to civilians, with longer range and better staying power. One method under development is by increasing autonomy on the drone itself. Eventually, drones may have the technical ability to make even lethal decisions autonomously: to respond to a programmed set of inputs, select a target and fire their weapons without a human reviewing or checking the result. Yet the idea of the U.S. military deploying a lethal autonomous robot, or LAR, is sparking controversy. Though autonomy might address...