The term that describes a duty that is enforced by a court and where non-fulfilment may incur a penalty.

A common clause in contracts that essentially frees both parties from liability or obligation when an extraordinary event or circumstance beyond the control of the parties such as war, strike, riot, crime, or an event known as an act of God (such as a hurricane, flooding, earthquake, volcanic eruption etc.), prevents one or both parties from fulfilling their obligations under the contract. In practice, most force majeure clauses do not exclude a party’s non-performance entirely, but only suspends it for the duration of the force majeure event.