The 'Parol Evidence' Rule

Invalidation by misrep or mistake

If a claimant finds out something in the contract is false then he can introduce evidence

The 'parol evidence' rule means that

If a contract is in writing, then any spoken or other evidence that contradicts or adds to the written agreement would be dismissed

If written agreement only represents part of a larger agreement

J Evans & Son v Andrea Merzario (1976)

When the contract relies on fulfillment of an event

Pym v Campbell (1856)

Custom or trade usage

Term can be implied into a contract by trade or custom

Rectification - where it can be shown that the written agreement did not reflect the actual agreement

Webster v Cecil (1861)

Collateral contracts

Westminster Properties v Mudd (1958)