This paper considers possible future legislation that requires the exclusive use of autonomous cars. The author develops and defends a ‘Liberal Argument Against Mandated Autonomous Cars’, which argues that such a law would be incompatible with classical liberalism, provided that the following condition holds: In the event where the car must ‘choose’ between running over a young person or an old person, or both, autonomous cars are programmed to respond by running over old people in order to save young people. Such a law requiring the use of these cars, provided that these assumptions hold, would violate the important value in classical liberalism that all individuals ought to be treated equally before the law. The paper concludes by arguing that alternative ways of dealing with this problem come with their own set of unpalatable problems.