There are many defences to the non-performance of a construction contract. Some have been touched upon earlier, and they include fraud, misrepresentation and mistake. All of these “excuse” performance by one party to the contract and, in the case of mutual mistake, both parties. This chapter deals with the other defences to performance, most notably force majeure and frustration. As discussed earlier, in the UK, if a contract becomes impossible to perform, or is only able to be performed in a manner substantially different from that originally agreed between the parties, then the doctrine of “frustration” may apply and the contract can be terminated. This may not be in the interests of either of the parties who may wish the contract to be suspended, rather than terminated, for the duration of the frustrating event, or for a specific period. In contrast, where the delay or failure to perform a contract by a party for reasons beyond its control occurs, then the doctrine of “force majeure” may apply, which, instead of terminating the contract, generally results in suspension of contractual obligations while the uncontrollable event is in progress.