Kuwait Court of Cassation principle number 1531

Where a contractual relationship exists between the parties to the dispute, no enrichment action lies. The limits and scope of this rule. If delivery of the thing not due was made outside the scope of the contract, even on the occasion of its performance, it lacks cause, and the provisions of the contract do not apply unless the obligation to return is required under the contract. Example. - Whoever receives something to which he is not entitled must return it. Whether the lack of entitlement arises from a factual circumstance or a legal consideration. Is immaterial. - Receipt of what is not due. As a general rule, sufficient to impose the obligation to return upon the recipient.