For decades, the greater part of efforts to improve regulatory frameworks for research ethics has focused on informed consent procedures; their design, codification and regulation. Why is informed consent thought to be so important? Since the publication of the Belmont Report in 1979, the standard response has been that obtaining informed consent is a way of treating individuals as autonomous agents. Despite its political success, the philosophical validity of this Belmont view cannot be taken for granted. If the Belmont view is to be based on a conception of autonomy that generates moral justification, it will either have to be reinterpreted along Kantian lines or coupled with a something like Mill's conception of individuality. The Kantian interpretation would be a radical reinterpretation of the Belmont view, while the Millian justification is incompatible with the liberal requirement that justification for public policy should be neutral between controversial conceptions of the good. This consequence might be avoided by replacing Mill's conception of individuality with a procedural conception of autonomy, but I argue that the resulting view would in fact fail to support a non-Kantian, autonomy-based justification of informed consent. These difficulties suggest that insofar as informed consent is justified by respect for persons and considerations of autonomy, as the Belmont report maintained, the justification should be along the lines of Kantian autonomy and not individual autonomy.