non-delegable duty

Definition 1

General: Performance of an obligation that cannot be delegated to a third (non-contracting) party under the terms of a contract. If delegated, the second (contracting) party may exercise its right to refuse to accept the performance.

Definition 2

Contracts: Performance of an obligation the delegation of which is not prevented but which (even if delegated) remains the responsibility of the obligor. An employer, for example, remains liable for the safety of the employees at work, even if an external entity is hired for monitoring and ensuring compliance with the safety requirements.