Coercive practices are relatively common in mental healthcare, but coercion is ethically problematic because it involves acting against an individual's autonomy. However, coercion is often poorly defined in mental health literature, resulting in problems in considering coercion from an ethical perspective. This paper challenges the traditional paternalistic justification for coercive practices in mental healthcare, and argues that the failure to make a conceptual distinction between what counts as coercive practice and what justifies coercive practice results in instances of unjustified use of coercion. It also results in the failure to recognize other justifications for coercive practice. We propose a broad definition of coercion that recognizes the prevalence of coercion in mental healthcare. In particular, we wish to recognize the potential for persuasion and manipulation of clients' wishes to be coercive. We argue that there should be a prima facie ban on coercion in mental healthcare, and that the use of coercive practices needs to be justified in the specific circumstances of each case. The presupposition that mental illness involves limited autonomy cannot be taken to justify use of coercion. We outline a principle of least coercive intervention that we think has the potential to lessen the prevalence and extent of coercion in mental healthcare.