What is a key condition for performance to be excused under impracticability?

Performance can be excused under the doctrine of impracticability when an unforeseen event significantly changes the nature of the contractual obligations, making it extremely difficult or impractical for a party to fulfill their duties. This doctrine serves to relieve a party from obligations when circumstances arise that were not anticipated at the time of contract formation.

In this context, the key condition is that the event causing the impracticability must be unforeseen by the parties at the time they entered into the contract. If the event was foreseeable, then the parties likely should have accounted for it in their agreement, and thus the performance would not typically be excused. The essence of this principle is to maintain fairness in contractual dealings by recognizing that certain unpredictable events can render performance infeasible or excessively burdensome.

In contrast, other options may imply conditions that do not meet the strict requirement for impracticability, such as mutual agreements or the need to seek alternatives, which are not necessary to invoke the doctrine successfully.