[Bartweiss]

I wish the article had taken this question more seriously. Impracticability is a defense under contract, but a fundamental requirement in the US test is:

> "an occurrence of a condition, the nonoccurrence of which was a basic assumption of the contract"

Impracticability is not a defense against signing stupid or damaging contracts; it specifically releases a party when circumstances change such that a contract is no longer reasonable. Standard examples are things like the outbreak of war or a supply chain collapse, which don't render a contract literally impossible to fulfill but do place fulfillment outside the domain of any reasonable effort.

Defending against conditions which were already in place when a contract was signed is far harder, and even impossibility is not necessarily a defense if the impossibility is obvious at the time of signing. The only common defense I know of against conditions present at the time of signing is illegality, which of course comes up quite often with things like noncompete clauses.

The misuse complaint at least looks plausible, but I'm pretty baffled by the appeal to impracticability.

[VanL]

Here is the analysis: Let's think about the context where this would come up: A party ("Service") takes the SSPL'd MongoDB and implements a service. Service releases some code based on a good faith interpretation of the scope of the release necessary. There is a dispute between MongoDB and Service as to the scope of the necessary code release.

In the ensuing lawsuit, Service raises misuse and argues that the scope is ambiguous. Leaving aside the misuse argument, a court could either a) find for Service, thus restricting the scope of the code to be delivered, or b) find for MongoDB, thus giving rise to an immediate defense of frustration/impracticability, which would undo the contract.

[Bartweiss]

Interesting, thanks very much. I hadn't realized that a new court interpretation of a contract could form the unforeseen circumstance for a defense.