Liquidated damages (also referred to as liquidated and ascertained damages) are damages whose amount the parties designate during the formation of a contract for the injured party to collect as compensation upon a specific breach (e.g., late performance).
When damages are not predetermined/assessed in advance, then the amount recoverable is said to be 'at large' (to be agreed or determined by a court or tribunal in the event of breach).
Generally, at common law, a liquidated damages clause will not be enforced if its purpose is to punish the wrongdoer/party in breach rather than to compensate the injured party (in which case it is referred to as a penal or penalty clause). One reason for this is that the enforcement of the term would, in effect, require an equitable order of specific performance. However, courts sitting in equity will seek to achieve a fair result and will not enforce a term that will lead to the unjust enrichment of the enforcing party.
In order for a liquidated damages clause to be upheld, two conditions must be met.
Damages that are sufficiently uncertain may be referred to as unliquidated damages, and may be so categorized because they are not mathematically calculable or are subject to a contingency which makes the amount of damages uncertain.
For example, suppose Neal Townsend agrees to lease a store-front to Richard Odness, from which Richard intends to sell jewelry. If Neal breaches the contract by refusing to lease the store-front at the appointed time, it will be difficult to determine what profits Richard will have lost because the success of newly created small businesses is highly uncertain. This, therefore, would be an appropriate circumstance for Richard to insist upon a liquidated damages clause in case Neal fails to perform.
In the case of construction contracts, courts have occasionally refused to enforce liquidated damages provisions, choosing to follow the doctrine of concurrent delay when both parties have contributed to the overall delay of the project.
Contracts in the NEC3 family use the term 'low service damages' (optional clause X.17) and generally include a Low Service Damages Schedule.