Deals & Cases
Breach of Contract | Defense Against and Dismissal of a Claim for Return of Unjust Enrichment Asserting Breach of Contract
To respond to a plaintiff who filed a lawsuit for return of unjust enrichment asserting breach of contract, the client requested the assistance of Daeryun.
The specialist attorney led to a judgment dismissing the plaintiff's claim.
1. The Client Who Was Sued for Return of Unjust Enrichment for Breach of Contract
The account of the client, who was sued for return of unjust enrichment on the ground of breach of contract, is as follows.
How the Case Arose

The client is the representative of a corporation engaged in the transportation of large cargo, and the corporation it operated had been responsible for tasks such as schedule management, dispatch coordination, and connecting carriers for transportation jobs entrusted by its business partners.
In this process, the client carried out the work by connecting some of the transportation tasks to outside carriers, and Employee A (hereinafter the “plaintiff”) performed transportation work within this structure through the client's arrangement.
In return for this, the plaintiff continued the work for several years, receiving settlement of the transportation fees after a brokerage fee of about 7 percent was deducted.
However, after the transactions ended, the plaintiff asserted that the brokerage fee had been excessively deducted during the past settlement process and filed a lawsuit for return of unjust enrichment on the ground of the client's breach of contract.
The client thereupon came to request the assistance of a specialist attorney at Daeryun Law Firm.
The Specialist Attorney's Assistance in the Breach of Contract Matter
1) An Objective Rebuttal to the Plaintiff's Assertions
The specialist attorney secured the tax invoices and settlement records for the transportation fees that the client had paid to the plaintiff and highlighted the point that the plaintiff had, for a long period, raised no objection to and had acquiesced in this settlement method.
In addition, on the basis of message records and the like, the attorney argued that the plaintiff had maintained a close relationship with the client and had been aware of the internal circumstances, emphasizing that asserting unjust enrichment after the fact was not reasonable.
2) A Rebuttal to the Breach of Contract Assertion Through Precedent
The specialist attorney, on the basis of Supreme Court Judgment 2008Da44368 of June 24, 2011, which held that ‘where the terms of a contract are not clear, the contract must be interpreted by comprehensively considering the circumstances of its conclusion and the parties' actual course of dealing’, argued that no agreement itself fixing the brokerage fee at a specific rate existed between the plaintiff and the client.
In particular, the attorney emphasized that, in light of the fact that the plaintiff had performed the settlements for several years without objection to the settlement amounts, an assertion of unjust enrichment premised on breach of contract could not be established.
Claim for Return of Unjust Enrichment Based on Breach of Contract, Plaintiff's Claim Dismissed
The court recognized that the plaintiff had, for a long period, raised no objection to and had accepted the method of settling the transportation fees, and that no express agreement fixing the brokerage fee at a specific rate existed.
Accordingly, the court determined that the breach of contract asserted by the plaintiff was not established and that the claim for return of unjust enrichment likewise could not be accepted.
The court therefore rendered a judgment dismissing the plaintiff's claim.
2. The Concept of a Claim for Return of Unjust Enrichment for Breach of Contract
A lawsuit for return of unjust enrichment, which is raised in connection with breach of contract, is a legal procedure requiring that, where another person has obtained a benefit without a legally justifiable reason, the benefit be returned.
‘Without a legally justifiable reason’ does not necessarily refer only to unlawful conduct.
The conduct need not be unlawful, and if there is evidence capable of specifically proving the unjustifiable manner in which the benefit was obtained, a lawsuit may be filed.
Requirements for Establishing a Claim for Return of Unjust Enrichment
Category | Content |
Existence of a benefit | The opposing party must have actually obtained a benefit in property |
Occurrence of a loss | There must be, on the claimant's side, a loss corresponding to that benefit |
Causal relationship | There must be a causal relationship between the opposing party's benefit and the claimant's loss |
Absence of a legal cause | There must be no legitimate legal basis for the opposing party's benefit |
3. If You Have Been Sued for Return of Unjust Enrichment for Breach of Contract, How to Respond
The fact that a lawsuit for return of unjust enrichment has been filed in connection with breach of contract does not necessarily mean that liability will be recognized.
The determination may vary greatly depending on how the terms of the contract, the trade practices, and the settlement process are organized.
Therefore, from the moment the complaint is received, the key is to respond calmly by separating the facts from the legal principles.
Response Strategy
1) You Must First Accurately Identify the Structure by Which the Unjust Enrichment Is Said to Have Arisen and Then Respond
Where multiple contractual relationships or transactions are intertwined, you must require that it first be specified from which legal relationship the ‘unjust enrichment’ asserted by the opposing party arose.
2) You Must Clearly Point Out Who Bears the Burden of Proof
In a lawsuit for return of unjust enrichment, the opposing party must prove the occurrence of the benefit and the absence of a legal cause, so where the materials are insufficient or amount to no more than indirect evidence, you must actively point this out to highlight the limits of the claim.
3) You Must Counter the Opposing Party's Arguments on Prescription and Legitimate Performance With Legal Principles
Because disputes are anticipated over matters such as the completion of the extinctive prescription, legitimate payment under the contract, and an already concluded settlement relationship, a systematic rebuttal grounded in precedent and legal principles is important.
If you have been sued for return of unjust enrichment for breach of contract, a response based on an accurate analysis of the structure and issues of the matter is necessary.
Daeryun Law Firm forms a task force of 1 to 20 members, including specialist attorneys, and provides stage-by-stage assistance from analysis of the contractual relationship to organization of evidence, review of precedent, and the litigation response.
If you need a legal response in connection with a lawsuit for return of unjust enrichment, we encourage you to seek assistance through a 🔗legal consultation reservation.

This content is based on actual cases handled by Daeryun Law LLC and has been partially adapted. All copyrights belong to Daeryun Law LLC.
Unauthorized reproduction, copying or distribution may result in legal action under applicable laws.
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