Contracts II
Restatement Second of Contracts § 261
Discharge by Supervening Impracticability
Where, after a contract is made, a party's performance is made impracticable without his fault by the occurrence of an event the non-occurrence of which was a basic assumption on which the contract was made, his duty to render that performance is discharged, unless the language or the circumstances indicate the contrary.
Copyright, The American Law Institute