Unjust enrichment and the law of contract increasingly in both common law and civil law jurisdictions lawyers are seeking to formulate a law of restitution that can provide a reliable remedy in unjust enrichment actions. Defining unjust enrichment unjust enrichment occurs when party a confers a benefit on party b without party a receiving the restitution as required by law in general unjust enrichment claims happen when there is an agreement between two parties an example would be if party a fulfills their part of the agreement while party b does not fulfill their part of the agreement it could be tempting to define unjust enrichment as a gift but it is important to distinguish between the two a gift . Unjust enrichment and construction contracts as stated above a claim for unjust enrichment will fail where the rights and remedies of the parties are determined by a valid contract so for example where a variation to a contract occurs the contractor must claim under the variation provisions of the contract only in cases where there are no variation provisions in the contract or the variation falls outside of the variation provisions may a claim for unjust enrichment succeed