This is the most commonly accepted way of effectively changing the terms of a commercial contract. The original contract is often a term (known as “no oral amendment”) that explicitly states that the only possibility of amending the contract is written with the agreement of both parties. In the event of a dispute over whether the parties have entered into a valid agreement to renew the contract, the Tribunal will rule on the issue on the relevant facts, taking into account the usual rules of interpretation of the contract. When the parties amend a contract in writing, it is generally easy for a party asserting its rights to prove the agreed amendment by referring to a variation agreement or the exchange of emails. Similarly, a party relying on an oral amendment should be able to determine how the amendment agreement was concluded. However, if one party says that a contract was different by moderate behaviour, things can be a little more complex. In C- S Associates UK Ltd/Enterprise Insurance Company plc, the Commercial Court ruled. The clause stipulated that the parties were not bound by oral agreements or even non-formal written documents, but did not insist on handwritten signatures, paper documents or the fact that the signatures of both parties must be on the same document. The Tribunal did not find that the electronic documents, including an electronic exchange signed on behalf of both parties, did not meet the requirements of the clause, provided, of course, that the other requirements relating to the drafting and modification of the contract, such as the intention to be linked. B are also brought together. In the whirlwind of the economy, written agreements sometimes cannot follow trade developments; and when disputes arise, the parties may find that their contracts do not say what they thought or reflect their actual practice. This can be frustrating and create uncertainty – are the parties bound by their initial agreement or has the treaty been amended? Often, the parties will attempt to amend the contract by inserting a new expiry date to keep the original contract on foot.

Although this seems to be the most practical method, it is unlikely to work. To amend a contract, both parties generally have to approve it before the changes take effect, preferably in writing. Unilateral derogations (i.e., where only one party can make an amendment) are only valid in certain circumstances, if they have been the subject of prior agreement. Persistent minor behaviour or offences (i.e., a party has repeatedly violated the treaty) may lead to a tacit change in the contract.