A contract may provide for liability to be excluded for any disruption to business continuity because of something abnormal and unforeseeable by the parties and beyond their control. This is known as 'force majeure'.

A traffic jam which leaves a traveller insufficient time to reach an airport is not a force majeure event. It is not a good reason for failing to catch a booked flight.

Contrast this with the sudden and total shutdown of all transport services serving the airport - which may be (depending on the airline's terms and conditions).

There may be protracted negotiations over what kinds of contingencies should be allowed for.

A customer will not wish to offer a supplier an easy escape route for failure to implement a system on time. A provider will not want a client's legitimate excuses to extend to failures to make a payment when required.

A long list of possible events, such as 'act of God, civil commotion, riot, war, explosion, accident, flooding, hurricane, earthquake, impossibility of obtaining raw materials, delays by third parties', makes reading the contract more interesting. But it is not always necessary to itemize those which are clearly beyond reasonable control.

While the force majeure circumstances continue, the party affected will not be at fault for delay or failure to carry out its obligations, and the time for delivery or implementation may be extended.

If they seem to be ongoing, say for more than three months, the wording may permit the contract to be brought to an end without any blame.

Rachel Burnett, solicitor. Burnett IT Legal Services.