The focus of this article is upon compassionate killings, that is, criminal cases where a parent/spouse has killed or assisted to die a child/spouse who was suffering from severe disabilities, debilitating injury, chronic or terminal illness. We argue that the partial defence of diminished responsibility, while appropriate for some cases, fails to acknowledge the compassionate and relational nature of these acts and thus fails to identify the quality of the harm committed. We also argue that the general defences of duress of circumstances and necessity, even if they were to be become available, are inappropriate. Developing the concept of ‘compassion’, which is a consideration in relation to prosecution for assisted suicide, we argue for the introduction of a partial defence of ‘compassionate killing’ which would reduce the offence from murder to manslaughter in recognition of the killing as a responsive, relational act of care.