We analyse the liberal ethics of noninterference in social choice. A liberal principle, capturing noninterfering views of society and inspired by John Stuart Mill's conception of liberty, is examined. The principle expresses the idea that society should not penalise individuals after changes in their situation that do not affect others. An impossibility for liberal approaches is highlighted: every social decision rule that satisfies unanimity and a general principle of noninterference must be dictatorial. This raises some important issues for liberal approaches (...) in social choice and political philosophy. (shrink)