Mercy is a form of charity towards wrongdoers that justifies punishing them less severely than they deserve according to justice. Three main objections to mercy, or its exercise by organs of the state - that it is irrational, unjust and procedurally unfair - are addressed in the course of defending mercy as a value that has a place in deliberation about criminal punishment. The paper draws on both the communicative theory of punishment and aspects of existing legal practice in mounting this defence.This is a pre-copy-editing, author-produced version. The definitive publisher-authenticated version of 'Mercy' PAS 103(1), 101-132 is available online at http://www.blackwell-synergy.co