Autonomous individuals are able to make decisions and effectively implement them, but heroin addiction can compromise this capacity.1 Very severely heroin-addicted persons are disabled in their efforts to implement decisions that would effectively promote their plans and values. For the purposes of this chapter, three salient pathways are available for a person in the grip of severe addiction. First, they may remain in their current situation, continuing to score and consume heroin untreated. Second, they may enter on a course of a maintenance dose of opiates. Or third, they may refuse to give up heroin, thereby triggering a legally mandated treatment regime involving detention in a facility where they receive clinical and transitional support services.2 In the second option, most typically a heroin substitute – either methadone or buprenorphine – is taken, but in some severe cases (about 5 per cent according to Alex Wodak), affected persons are resistant to this approach and in some jurisdictions heroin itself (diamorphine) is given.3 This is known as heroin-assisted treatment, or HAT.4