The report of the expert group on the review of the Mental Health Act has recommended that the requirement to consider the best interests of the person be replaced by a list of guiding principles, which focus on the autonomy of the individual. The implied rationale for this is that acting in our patients’ best interests may be a violation of their human rights. Dignity is being proposed as an alternative way of capturing ‘the positive aspects associated with best interests’, but it is not clear how dignity is preferable to best interests. Both approaches may help protect the most vulnerable from exploitation. However, unlike best interests, dignity can be used as a synonym for autonomy. Valuing autonomy as a means to an end (instrumental value) should be distinguished from valuing autonomy as an end in itself (intrinsic value). As the ultimate end of instrumental autonomy is invariably the person’s best interests, abandoning that principle renders instrumental autonomy obsolete, leaving intrinsic autonomy as the supreme value. As best interest, dignity and autonomy rarely conflict, the proposed changes may appear minor, but they are not. When such values do conflict, acting against our patients’ interests may become inevitable.