He works primarily in normative ethics, with a focus on the morality of defensive violence, the morality of war, and complicity. He also works on a variety of other issues in normative ethics, including: the moral analysis of coercion, the bases of compensatory liability, and the morality of mediating agency. He was awarded the Philosopher’s Annual Top Ten Papers of 2014 for his article ‘Moral Coercion’. He is currently authoring a book on complicity and the morality of war, and is co-editing the forthcoming Oxford University Press volume ‘The Ethics of War: Essays’.