Contractual impossibilities are known as supervening impossibilities.

Supervening impossibility refers to a situation where the performance of a contract becomes impossible or impracticable due to an unforeseen event or change in circumstances that occurs after the contract is formed. These events are beyond the control of the parties involved and are not contemplated at the time of entering into the contract.

Supervening impossibility can arise due to various reasons such as natural disasters, government regulations, war, and acts of God. For example, if a contract is entered into for the sale of a specific item, but the item is destroyed in a fire before it can be delivered, the performance of the contract becomes impossible due to the supervening impossibility of the item being destroyed.

The doctrine of supervening impossibility is based on the principle of fairness and equity. It recognizes that it would be unjust to hold a party responsible for the non-performance of a contract if the impossibility is due to circumstances beyond their control. In such cases, the affected party may be discharged from their obligations under the contract.

It is important to note that supervening impossibility does not apply to situations where the impossibility was foreseeable or could have been prevented by taking reasonable precautions. The event or change in circumstances must be truly unforeseeable and unavoidable for supervening impossibility to be invoked.

In conclusion, supervening impossibility refers to the situation where the performance of a contract becomes impossible or impracticable due to an unforeseen event or change in circumstances that occurs after the contract is formed. It is a recognized doctrine that allows the affected party to be discharged from their obligations under the contract.