The authors establish that in the West mercy in public life, in particular as acts of judges and governors, underwent a wrongful decline. This decline is an effect of the tension between mercy and justice that grew during the transition of medieval, Christian into modern, secular law and justice. To prove this, the authors present a broad historical overview. Eventually, they argue in favour of an incidental application of mercy in public life, under strict conditions. However, in a secular society and law system mercy can be made acceptable only for the political and public debate. In this situation, an appeal to a more neutral sounding virtue such as compassion will be more convincing.