Illegal Contracts Fail but Restitution Survives: Implications for Cross-Border Remittance from Wong Chi Hung v Lo Wing Pun [2026] HKCFA 14

Introduction

The Hong Kong Court of Final Appeal (CFA)’s decision in Wong Chi Hung v Lo Wing Pun [2026] HKCFA 14 is a significant decision for cross-border transactions, especially those involving informal remittance practices across border. The judgment clarifies the interaction between foreign illegality and contractual claims or claims in unjust enrichment under Hong Kong law.

This article only focuses on the implications of cross-border remittance practices but does not address CFA’s discussion on stare decisis and the binding effect of overseas authorities.

 

Background

The Plaintiff sought to convert RMB1 million held in the Mainland into HKD payable in Hong Kong. An exchange agreement was entered into in Hong Kong, pursuant to which the Plaintiff would deposit RMB1 million into a Mainland account designated by the Defendant, who would in return remit the equivalent amount in HKD at an agreed exchange rate (the Agreement).

Such arrangement constituted an unlicensed currency exchange transaction and was illegal under the PRC law. The transaction ultimately failed as the Plaintiff paid the RMB deposit (which was subsequently frozen by the PRC authorities due to a criminal investigation) but the corresponding HKD remittance had never been made. The Plaintiff therefore commenced proceedings in Hong Kong, advancing a contractual claim, or alternatively a claim in unjust enrichment seeking restitution of the RMB 1 million.

 

Rulings

Illegality and Contractual Claim: the Ryder Framework

The contractual claim was analysed by reference to the principles as set out in Ryder Industries Ltd v Chan Shui Woo [2015] 18 HKCFAR 544. That case considered international comity and Hong Kong public policy, and the Court eventually limited the enforcement of the contract, as giving effect to it would involve or facilitate serious foreign illegality. Turning to the present case, the original position taken by the District Court was to treat the Agreement unenforceable on the basis that its performance necessarily involved illegal conduct under Mainland foreign exchange regulations. The Court of Appeal expressed reservations about this approach, noting that payment of HKD in Hong Kong itself did not involve illegality, and that foreign illegality should not excuse the non-performance of a Hong Kong law obligation to make payment in Hong Kong. CFA shared the same reservation but did not rule on such issue as the central issue of the current appeal only concerned the restitution claim.

Distinction Between Contractual Claim and Unjust Enrichment Claim

CFA made clear that the issues arising in the case required a distinction between contractual claims and claims in unjust enrichment, but not merely on the basis of the Ryder Framework as discussed above. CFA distinguished between (1) contractual claims, which are concerned with enforcing the parties’ agreed exchange of value; and (2) restitutionary claims, which seek to reverse an unjust enrichment with the basis of a failure transfer. These claims are conceptually distinct and serve different rationales and objectives. CFA proceeded on the assumption that the contract was unenforceable, and this case was not ultimately decided on contractual enforceability. Instead, the decisive issue was whether the illegality of the underlying transaction would defeat a claim in unjust enrichment.

In fact, an argument was advanced by the Defendant that an award of restitution would amount to an enforcement of the illegal Agreement “by the backdoor”, effectively allowing the Plaintiff to achieve the same economic outcome as the performance of the Agreement. CFA rejected this argument and held that restitution aims to unwind but not to enforce the transaction. The similarity in economic effect to contractual performance as argued was superficial, and the juridical basis and consequences were fundamentally different.

The Impact of Illegality on Unjust Enrichment Claim

CFA adopted a flexible approach in Patel v Mirza [2017] AC 467 (over Tinsley v Milligan [1994] 1 AC 3460), which reaffirmed that restitution should be available notwithstanding illegality, and the denial of restitution is justified only in rare and exceptional circumstances, typically those involving serious criminality or cases where granting relief would undermine the integrity of the legal system.

Applying such approach, CFA held that there was no basis for denying restitution. The illegality in this case was peripheral rather than central from the Plaintiff’s perspective, and there was no suggestion that such conduct would be comparable to a serious criminal case.

 

Key Takeaways: Implications for Cross-Border Remittance Practices

CFA concluded that where a Hong Kong law contract is unenforceable by reason of foreign illegality, a claim in unjust enrichment arising from a total failure of consideration would generally succeed, unless the grant of restitution would offend the principles of comity or endorse serious foreign illegality.

The factual matrix of this case reflects a common commercial phenomenon. In fact, informal arrangements for converting RMB held in the Mainland into HKD payable in Hong Kong, involving non‑bank intermediaries and Mainland accounts designated by Hong Kong counterparties, remain common notwithstanding PRC foreign exchange controls. This case squarely addresses the legal consequences when such transactions fail to proceed.

The case confirms that while informal remittance arrangements may collapse at the contractual level due to illegality, such illegality does not automatically shield recipients from unjust enrichment claim. Parties who have lost funds due to regulatory intervention may still recover via unjust enrichment claim. Hence, this judgment reflects a pragmatic judicial response to cross‑border realities.