Definition: Not a true contract, but an obligation imposed by the law to prevent one party from being unjustly enriched at the expense of another.
Example: A decorator mistakenly decorates the wrong house with Christmas lights. If the homeowner benefits and keeps the display, they may be required to pay a reasonable amount.
Case law: Fibrosa SA v Fairbairn Lawson Combe Barbour Ltd [1943][1]
[1] Fibrosa Spolka Akoyjna v Fairbairn Lawson Combe Barbour Ltd [1943] AC 32
