 Unfortunately, the literature has paid little attention to the distinction made above between internal psychological barriers and external barriers. For example, Appelbaum, Lidz, and Klitzman (2009) set out to chart the domain of voluntariness, but ended up focusing exclusively on external factors such as coercion and undue inducement. They are explicit that since the law has traditionally treated voluntariness in an external fashion—as the absence of force, coercion or undue inducement—they have sought to explain only these kinds of phenomena. However, this begs the ethical question of whether there really might be internal barriers to meaningful choice and if so, whether the law ought to recognize them even if it currently doesn’t. Other theorists such as Laura Weiss Roberts (2002a,b) have explored a wider range of factors that might affect voluntariness, but with the result that far too much is included (as opposed to too much being excluded, as above). Approaches like hers fail to make crucial distinctions between strong, though understandable, feelings a person might have in response to a situation (but which need not undermine the voluntariness of a choice) and more plausible threats to voluntariness such as addiction. The difficulty is precisely to distinguish genuine impediments to voluntary choice from the many and varied internal factors that can influence choice, and/or lead to imprudent or unwise choices. Much work remains to be done here. 