Agent-regret
The particular regret a person feels for harm they brought about through their own action, even when they were not at fault for it. It turns on agency rather than blame: a driver who kills a child that darts into the road, blameless in every legal and moral sense, still feels something different from a mere bystander — and would be a worse person if they did not.
Bernard Williams's technical term for the regret one experiences as the agent who caused harm, even when one is not strictly to blame for the harm. Distinct from ordinary regret in that it is keyed to one's agency rather than to one's culpability: the lorry-driver who runs over a child who darts into the road through no fault of the driver still experiences agent-regret, and would be a worse person if he did not.
Etymology§
Introduced by Williams in his 1976 essay "Moral Luck" (in Proceedings of the Aristotelian Society, reprinted in the volume Moral Luck, Cambridge UP, 1981) and developed at length in Shame and Necessity (UC Press, 1993). The term is a technical hyphenation: agent-regret as the compound construct, to mark its difference from regret simpliciter.
For the moral-injury literature, agent-regret is the philosophical construct that makes sense of the moral wound of soldiers whose participation in harm was structured by the situation rather than chosen freely — the conscript, the soldier ordered into an atrocity-producing situation, the medic forced into a triage decision by resource constraints. The standard Anglo-American moral-theory framework, on which guilt is keyed to culpability and blame is keyed to free choice, leaves these agents with no available moral emotion that fits their position. They were not strictly to blame; ordinary regret is too thin to register what they participated in; Williams's agent-regret is the construct that fits.
The inheritance into the moral-injury literature is partly direct (through Sherman's Afterwar, which cites Williams explicitly) and partly indirect (through the general circulation of the construct in late-twentieth-century moral philosophy). Shay's account of betrayal-of- thémis does the same kind of work from the classics-clinical side: the soldier whose moral wound is registered by his thumos as a response to a situation he did not create is, philosophically, an agent-regret case. The construct is the deep philosophical machinery on which the moral-injury literature operates whether or not particular clinical-research papers cite Williams.