A robust, if not absolute, prohibition on treating people merely as a means seems to sit at the core of common sense deontological morality. But the principle prohibiting such treatment, the ‘means principle’ (MP), has been notoriously hard to defend: both the subjective, intention-focused and the objective, causal-role-focused interpretations of what it means to use someone as a means face potent objections. In this paper, my goal is not to defend the MP, but to articulate and defend a new principle, (...) which I call the Restricting Claims Principle (RCP), that explains why a person’s causal role is morally significant. The RCP broadens the basic frame of relevant considerations from the MP’s concern with the dyadic relationship between agent and patient to a global balance of patient-claims on an agent. It distinguishes two kinds of patient-claims that weigh in that balance: restricting and non-restricting. In most cases, these can be distinguished as follows: Restricting claims, if respected as rights, would restrict an agent from doing what she could otherwise permissibly do if the claimant (or his property) were absent; non-restricting claims, if respected as rights, would not in that way restrict an agent. Only restricting claims press to make others worse off than if the claimant were absent. The RCP holds that restricting claims must therefore be substantially weaker than non-restricting ones. The claims of those who would be used as a means are non-restricting, while the claims of those who would be harmed as a side effect are restricting. Thus the RCP can account for the same cases (mostly) as the MP, without having to rely on the MP to do so. (shrink)