The context- and person-specific nature of the Mental Capacity Act 2005 (MCA) in England and Wales means inherent indeterminacy characterises decision-making in the Court of Protection (CoP), not least regarding conflicting values and the weight that should be accorded to competing factors. This paper explores how legal professionals frame and influence the MCA's deliberative and adjudicative processes in the social space of the courtroom through a thematic analysis of semi-structured interviews with legal practitioners specialising in mental capacity law and retired judges from the CoP and the Courts of Appeal with specific experience of adjudicating mental capacity disputes. The concept of the ‘human element’ offers important new insight into how legal professionals perform their roles and justify their activities in the conduct of legal proceedings. The ‘human element’ takes effect in two ways: first, it operates as an overarching normative prism that accounts for what good practice demands of legal professionals in mental capacity law; secondly, it explains how these professionals orientate these norms in the day-to-day conduct of their work. The ‘human element’ further presents challenges that demand practical negotiation in relation to countervailing normative commitments to objectivity and socio-institutional expectations around professional hierarchies, expertise, and evidential thresholds.

This paper draws upon the civic republican tradition to offer new conceptual resources for the normative assessment of mental capacity law. The republican conception of liberty as non-domination is used to identify ways in which such laws generate arbitrary power that can underpin relationships of servility and insecurity. It also shows how non-domination provides a basis for critiquing legal tests of decision making that rely upon ‘diagnostic’ rather than ‘functional’ criteria. In response, two main civic republican strategies are recommended for securing freedom in the context of the legal regulation of psychological disability: self-authorisation techniques and participatory shaping of power. The result is a series of proposals for the reform of decisional capacity law, including a transition towards purely functional assessment of decisional capacity, surer legal footing for advanced care planning, and greater control over the design and administration of decision making capacity laws by those with psychological disabilities.