Amendment
The art of varying the agreed terms of a contract.
It requires both parties to agree to the amendment. That’s more or less it.
No oral modification
What of the Mobius loop thrown by a clause that provides this agreement may not be amended except in writing[1], or this agreement may not be amended at all?
A recent supreme Court case had a thing or two to say about that.
{{Casenote|Rock Advertising Limited|MWB Business Exchange Centres Limited]] concerned just such a non-oral modification clause. Could it really work? Surely, a merchant’s freedom to vary his affairs in a way the common law decrees effective is paramount. Can such a provision really double-entrench itself?
The Court of Appeal thought not. A fellow can agree whatever he chooses, however he chooses – in writing, orally or by conduct[2]. Following that general principle, a “no oral modification” clause (a “NOM” clause) would not prevent him later making a new oral contract to vary the original contract.
Good, that’s that all sorted and we can now all move on to more important issues of the d —
BUT WAIT. The Supreme Court disagrees. Lord Sumption (for it was he) dismissed this “fallacious” reasoning: a chap’s autonomy operates until he has made his contract; thereafter only as far as the original contract allows.
Quoth milord: “The real offence against party autonomy is the suggestion that they cannot bind themselves as to the form of any variation, even if that is what they have agreed.”
But what if contracting parties have relied on a non-compliant variation in good faith, and by their conduct abided by it for a good period? as have so many of his brother judges done in the past, here Lord Sumption looked lovingly towards the courts of chancery in the defendant’s aid. A wringed party might seek to argue estoppel. However, the scope of this estoppel will be limited; "at the very least, there would have to be some words or conduct unequivocally representing that the variation was valid notwithstanding its informality and something more would be required for this purpose than the informal promise itself".