The world limit is 2,000 words, inclusive of footnotes/endnotes but exclusive of bibliography. It is applied strictly. There is no lower limit but you should not aim to write much less than the limit, and certainly not less than 1,500 words.
Some recommended reading:
M.H. Kramer, N.E. Simmonds and H. Steiner A Debate over Rights (Oxford, 2000), available online via the library. Three key contributions to the rights debate.
(Since you are being ask for the Interest theory only you probably would not have to read the whole book and just read the following chapters:
-Krammer: 2. Right without trimmings.
– Simmonds: 1. Background; 2. Fundamental issues; 5. The interest theory of rights
– Steiner: 1. Preliminary Intuitions about Rights; 5. Some real problems with the interest Theory)
N. MacCormick Children s Rights: A Test-Case for Theories of Rights , in his Legal Right and Social Democracy: Essays in Legal and Political Philosophy (Clarendon, 1984), available online via the library. Neil MacCormick gives the classic argument that its inability to attribute rights to children sinks the Will Theory.
H.L.A. Hart Are There Any Natural Rights Philosophical Review 64 (1955): 175-91, on the Moodle, and in the Waldron collection. This is difficult, not least because Hart doesn t use the same terminology as us. Nevertheless, it s important, because it contains three important arguments: (a) that the will theory is mostly correct, (b) that we should bite the bullet and accept that infants don t have rights, and (c) the will theory s being correct depends on there being at least one interest-based right, namely the equal right to freedom.
R. Cruft Rights: Beyond Interest Theory and Will Theory in Law and Philosophy 23 (2004): pp. 347-97, and on the Moodle. Cruft criticises both the Interest Theory and the Will Theory of rights, on the basis that they both diverge too far from everyday usage of the concept of rights.
Obviously, in addition to these readings, you should consider finding reading elsewhere.
N.B your essay should have a narrow focus. Ideally, it should tackle one key objection in detail.
Other useful introductory links: