It is a truism that there are erroneous convictions in criminal trials. Recent legal findings show that 3.3% to 5%of all convictions in capital rape-murder cases in the U.S. in the 1980s were erroneous convictions. Given this fact, what normative conclusions can be drawn? First, the article argues that a moderately revised version of Scanlon’ s contractualism offers an attractive moral vision that is different from utilitarianism or other consequentialist theories, or from purely deontological theories. It then brings this version of Scanlonian contractualism to bear on the question of whether the death penalty, life imprisonment, long sentences, or shorter sentences can be justified, given that there is a non-negligible rate of erroneous conviction. Contractualism holds that a permissible act must be justifiable to everyone affected by it. Yet, given the non-negligible rate of erroneous conviction, it is unjustifiable to mete out the death penalty, because such a punishment is not justifiable to innocent murder convicts. It is further argued that life imprisonment will probably not be justified (unless lowering the sentence to a long sentence will drastically increase the murder rate). However, whether this line of argument could be further extended would depend on the impact of lowering sentences on communal security.