36 Theoretical error, real-world problems in this discussion the focus is not on the rights of noncitizens themselves, but on the implications for other groups: for citizens and others left behind. This is quite common.­ In­ her­ early­ work,­ even­ Martha­ Nussbaum,­ upon­ whose­ capabilities­ approach this book draws heavily in Chapter 9, assumes citizen-composition, and that a State’s obligations are principally to its own citizens. She uses the word ‘citizen’ without explanation and does not discuss the implications of noncitizenship. For example, in 2003, to indicate universality, she wrote that entitle ment is for all citizens, continuing: ‘to secure a right to citizens in these areas is to put them in a position of capability to function in that area.’36 Amartya Sen reflects­ on­ needing­ to­ ensure­ all­ ‘citizens’­ have­ access­ to­ development­ and­ a­ voice in society, but it is sometimes also unclear who he would include in that constituency.37­ In­ 2011,­ Nussbaum­ explicitly­ rejected­ justice­ theorising­ whose­ scope is limited to citizens.38 And yet citizenship is often seen as arbitrary, as a status of inherited privi lege, or an essentially ‘caste-like’ ‘rank of citizenship’.39 Despite this, the experi ence of formal citizenship is itself unequal and less secure than it could be. Here emerges another important role for noncitizenship. On one hand, class, race, ethnicity and gender, for example, can alter persons’ experiences of citizenship, so that there is an intertwining of citizenship with noncitizenship.40 On the other hand,­ some­ may­ want­ to­ reject­ aspects­ of­ citizenship,­ claiming­ an­ empowered­ noncitizenship.41 Noncitizenship and citizenship are not mutually exclusive. Rec ognising this makes it possible to identify and to address discrimination within the system in a new way. ­ For­ David­ Miller,­ a­ State’s­ right­ to­ exclude­ comes­ with­ the­ obligation­ to­ protect the equal status of all those living within its borders.42 For liberal com munitarians­ like­ Miller,­ there­ must­ be­ universal­ membership­ within­ a­ State,­ 36­ Martha­ Nussbaum­ (2003)­ ‘Capabilities­ as­ Fundamental­ Entitlements:­ Sen­ and­ Social­ Justice’,­ pp. 33–59 in Feminist Economics 9, p. 35, p. 7. 37 Amartya Sen (2009) The Idea of Justice, Allen Lane, London, pp. 352–355. 38­ Martha­ Nussbaum­ (2011)­ Creating Capabilities: The Human Development Approach, Harvard University Press, p. 128. 39 For example, Joseph Carens (1987) ‘Aliens and Citizenships: The Case for Open Borders’, pp. 251–273 in The Review of Politics 49(2),­p.­252;­Gregory­Vlastos­(1984)­‘Justice­and­Equal ity’, pp. 41–76 in Jeremy Waldron (ed.) Theories of Rights, Oxford University Press, p. 54. 40 For example, Elizabeth Anderson (2011) The Imperative of Integration, Princeton University Press;­Evelyn­Nakano­Glenn­(2004)­Unequal Freedom: How Race and Gender Shaped American Citizenship and Labor,­Harvard­University­Press;­‘Essays’­in­Tariq­Modood,­Anna­Triandafyl lidou and Ricard Zapata-Barrero (2006) Multiculturalism, Muslims and Citizenship: A European Approach.­ In­ Chapter­ 9,­ I­ also­ discuss­ this­ with­ regard­ particularly­ to­ the­ semi-fictional­ figure­ presented in Buchi Emecheta’s Second Class Citizen. See also Leti Volpp (2007) ‘Citizenship Undone’, pp. 25–79 in Fordham Law Review­75;­Niraja­Gopal­Jayal­(2013)­Citizenship and Its Discontents: An Indian History, Harvard University Press. 41 Developed in Chapter 6. 42­ David­ Miller­ (2005)­ ‘Immigration:­ The­ Case­ for­ Limits’,­ pp.­ 193–206­ in­ Andrew­ Cohen­ and­ Christopher Heath Wellman (eds) (2005) Contemporary Debates in Applied Ethics, Blackwell, p. 205.