Template:M summ 2002 ISDA 9(f)
Waiver: a place where the laws of the New World and the Old diverge. Those with an English qualification will snort, barking reference to Hughes v Metropolitan Railway and say Section 9(f) is inconsequential fluff; those acquainted with the Uniform Commercial Code will tread more carefully, lest it creates a course of dealing. Since the ISDA Master Agreement was designed with either legal system in mind, ISDA’s crack drafting squad™ came up with something that would work in either, even if it offends minimalists like the JC who hail from — or ply their trade in — the old country.
Different approaches to evidence of the contract in the UK and US
England and the US have taken different paths when it comes to respecting the sanctity of that four-cornered document representing the contract. Whereas the parol evidence rule gives the written form a kind of “epistemic priority” over any other articulation of the abstract deal in the common law, in the new world greater regard will be had of how the parties behave when performing their contract, and less significance on what at the outset they wrote down.
So whereas in England action to not insist upon strict contractual rights will have scarce effect on those rights (at best a waiver by estoppel might arise, at least until it is withdrawn[1]), in the United States Uniform Commercial Code[2] a “course of dealing” between the parties at variance with the written terms of their bargain will tend to override those written terms. Thus, by not insisting on the strict terms of her deal, an American risks losing that deal, and will be taken by the course of dealing to have agreed something else; whereas an Englishman, by granting such an indulgence, at worst suspends his strict contractual rights but does not lose them.
In this way the parol evidence rule is less persuasive in American jurisprudence than in British.