Part IV Rules Relating to Written Contracts, 27 The Status of Instruments: Forgeries, Deliberate Alteration, Non Est Factum , and Shams

Subject(s):

Construction of contract — Formation of contract — Interpretation of contract — Performance of contract — Types of contract or document and damages

This chapter considers two special doctrines: first, the ancient rule which discharges a contract by operation of law if it is materially altered, commonly known as the rule in Pigot's Case; secondly, non est factum. It begins with a discussion of the impact of forgery on a document, as a forged document is a legal nullity. The chapter then turns to the above-mentioned doctrines in more detail, by first exploring the original formulation of the deliberate alternation of instruments in Pigot's Case before discussing the modern scope of the rule. Next, the plea of non est factum (‘this is not my deed’) is then examined. Finally, the chapter considers the principles which apply where a document is alleged to be a ‘sham’.