 Decision relativity refers to the now almost universally accepted idea that an individual’s decisional capacity should be assessed relative to a specific decision, at a particular time, in a particular context (Buchanan &amp; Brock 1989: 18–20; Culver &amp; Gert 1990: 620; Zapf &amp; Roesch 2005). The requirement issues from the value placed on freedom to choose, along with the recognition of several facts. First, not all decisions require the same level of mental ability. Understanding all the facts relevant to making decision A might be much easier than understanding all the facts relevant to making decision B. The idea is to allow people to make the most use they can of the mental abilities they have.