[5] Henry Pigot was indebted to Benedict Winchcombe, and on 2 March 1611 they executed a bond by way of deed relating to the indebtedness.

At this point, some well-meaning but unknown person altered the deed to record this fact by inserting the words "Vicecomiti Comitatus Oxon" (Sheriff of the County of Oxford) immediately after the words Benedict Winchcombe, Esq and before the specification of the amount due.

[6] Coke held: when any deed is altered in a point material, by the plaintiff himself, or by any stranger, without the privity of the obligee, be it by interlineation, addition, rasing, or by drawing of a pen through a line, or through the midst of any material word, that the deed thereby becomes void.Much of Coke's judgment was pure obiter dictum.

The most recent edition of Chitty on Contracts describes the rule as:[8] If a promisee, without the consent of the promisor, deliberately makes a material alteration in a specialty or other instrument containing words of contract, this will discharge the promisor from all liability thereon, even though the original words of the instrument are still legible.Although the strict consequences of a party to the deed making a non-material alteration to the document appear harsh today, the case actually softened the effect of a much harsher line of earlier authorities.

[9]In 1791 the scope of the rule in Pigot's Case was extended from deeds to all contracts and other legal instruments by the decision in Master v Millar (1791) 14 TR 320.