Much contemporary discussion of mercy has focused on what I call ‘beneficent mercy’: compassionately sparing a person from harsh treatment that she deserves. Drawing on Seneca’s discussion of mercy, I articulate a different concept of mercy which I call ‘critical mercy’: treating a person justly when unjust social rules call for harsher treatment. Whereas beneficent mercy is grounded in recognition of imperfection in human individuals, critical mercy is grounded in recognition of imperfection in human institutions. I argue that political communities (...) have reason to authorize judges to grant critical mercy in criminal law. I contend with the objection that critical mercy appears to violate the ideal of the rule of law. I argue that where certain constraints are met, rule of law values in fact provide positive reason to authorize judges to grant critical mercy in criminal law. (shrink)