Others on the panel know more about this topic than I do, but since this question has gone unanswered for several days, here is one non-expert’s answer.

The most important 20^th-century work on Justice within the Anglo-American philosophical tradition is undoubtedly John Rawls’ Theory of Justice (1971). Rawls is primarily concerned with the issue of distributive justice – the question of how limited resources within a community could be fairly allocated among its members. Rawls contends that a just distribution is one in which all citizens have basic rights and liberties, and in which social and economic inequalities are arranged so as to be of greatest benefit of the least advantaged members of society. Rawls’ original book is difficult but readable even by non-specialists.

One of the most influential critiques of Rawls can be found in Robert Nozick’s Anarchy, State and Utopia (1974). Nozick maintains that what makes a distribution just is simply that it was arrived at as the result of a series of individually just transactions: no particular pattern of distribution is mandated or ruled-out in advance.

Introductory courses on the theory of justice typically include selections from each of these books, along with historical sources – often including selections from Plato’s Republic, Hobbes’ Leviathan, Locke’s Second Treatise on Government, and John Stuart Mill’s Utilitarianism—and contemporary writers – often including selections from Michael Sandel’s Liberalism and the Limits of Justice, and feminist writers such as Susan Moller Okin.

A particularly nice anthology – which includes selections from many of the texts listed above, along with a well-assembled collection of additional readings – is Robert Solomon and Mark Murphy (eds.) What is Justice? Classic and Contemporary Readings (Oxford 2000), whose table of contents can be viewed here.