Cross-chain transactions and blockchain interoperability allow for easy movement of assets and execution of smart contracts across blockchain networks. However, enforceability has significant legal challenges that are rooted in jurisdictional ambiguity geographically, regulatory inconsistency within the law, and evolving nature of smart contract enforceability. The foremost issue is jurisdictional ambiguity, because each blockchain is structured under a unique framework of regulation, therefore, it is often difficult to identify which law applies during disagreements. 

For instance, if a blockchain transaction involves parties from multiple jurisdictions, like California, Europe, and Asia, differences of opinion on law can lead to complicated enforcement. Smart contracts also complicate cross-chain transactions as they facilitate transactions by facilitating an automated process, but they are not universally agreed upon as enforceable or binding, which poses problems on liability for a court or regulatory authority that is interpreting and enforcing them.

Regulatory compliance, especially regarding securities law compliance, anti-money laundering (AML), or know-you-customer (KYC), is also a challenge about compliance and enforceability. For example, a digital asset may be compliant with securities laws in one jurisdiction and not in another, which makes it difficult to establish a standard form of compliance across multiple jurisdictions. Furthermore, the challenge of tracking illegal use across multiple chains is not conducive to the complicated nature of cross-jurisdictional regulatory compliance.

Determining liability and dealing with disputes that stem from any contract that occurs in cross-chain transactions is also confusing and unclear. Identifying who is responsible for an exploit, hack, or transaction failure can be complex, if not impossible, especially when interoperability protocols, such as blockchain bridges and oracles, introduce risks of third-party participation, without any firm legal obligations. Standard mechanisms for dispute resolution, such as litigation or arbitration, are almost meaningless in decentralized environments where parties may refrain from revealing personal identities.

Moreover, cross-chain agreements can be difficult to enforce given decentralized governance models that distance parties from accountability. Risk mitigation can be further provided by smart contract-based mechanisms; however, any underlying agreement should seek to include an in-built framework for dispute resolution to address accountability and legal recourse upon the contract being triggered.

For these reasons, the legal landscape of dispute resolution, regulatory compliance, and smart contract agreements will be required to adapt, to provide blockchain specific dispute resolution, regulatory guidance, and potential legal recognition of smart contracts. Absent this legal framework evolution, the enforceability of cross-chain transactions will remain unpredictable and complex, if not impossible, to enforce in a legal context.