Summary   The right of a person to make their own decisions but be protected from serious harm should cognitive capacity decline poses ethical and practical challenges for the law. The principle of supported decision-making enshrined by the UN Convention on the Rights of Persons with Disabilities 2006 has fuelled the search by law reform bodies for new statutory models or principles capable of better respecting autonomous choice and avoiding undue paternalism in the name of protection of the vulnerable. This paper selectively reviews some law reform models across the spectrum from guardianship and supported decision-making to durable powers of attorney or support. It argues that across these different legal settings there are shifting (and delicate) balance points to be found between competing ethical principles (such as autonomy and protection), adequate accountability and freedom from undue regulation, and “workability” (fidelity of practice to intended objectives).