What a Smart Contract Can and Cannot Do Legally
Self-executing code is often marketed as a replacement for lawyers, but English law treats a smart contract as a tool for performing an agreement, not a substitute for one.
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What a smart contract actually is
A smart contract is a piece of computer code, usually running on a blockchain, that automatically executes an action when certain conditions are met. Pay in a sum of cryptocurrency and a token is released; a payment date passes and funds transfer automatically; a flight is delayed and an insurance payout triggers without anyone submitting a claim.
The phrase is misleading because a smart contract is not always a contract in the legal sense, and it is not particularly smart. It is automation. It does exactly what its code says, nothing more and nothing less. Whether that code also creates binding legal rights and obligations is a separate question, governed by ordinary contract law, not by the technology.
The law does not care what language a contract is written in
England and Wales does not require a contract to be in English, in prose, or on paper. A contract needs an offer, acceptance, consideration and an intention to create legal relations. The Law Commission examined this question directly and concluded that a smart contract, or a legal agreement partly or wholly recorded in code, is capable of meeting these requirements under existing law. There is no need for new legislation to make code-based agreements enforceable in principle.
That means a smart contract can, in the right circumstances, be a real and binding legal contract. Two businesses can agree that their obligations to each other will be performed automatically by code, and a court can treat that arrangement the same way it treats a written agreement, provided the usual ingredients of a contract are present somewhere in the arrangement, whether in the code itself, in an accompanying written agreement, or in the parties’ conduct.
What it can genuinely do
A well-built smart contract can remove the need for one party to trust the other to perform, because performance happens automatically once agreed conditions are satisfied. This is useful for straightforward, objectively verifiable obligations: releasing payment on delivery, distributing royalties automatically when a sale occurs, or triggering a covenant when a financial ratio in a loan is breached. It can reduce the scope for one side to simply refuse to pay or deliver, and it can cut down on manual reconciliation and processing delays.
It can also serve as strong evidence of what happened and when, because blockchain records are typically time-stamped and difficult to alter retrospectively. That can be genuinely valuable if a dispute later arises over the sequence of events.
What it cannot do
Code cannot interpret intention, context or fairness. If the parties disagree about what an ambiguous clause meant, a court still has to construe the agreement using ordinary contractual interpretation principles. Code is precise about outcomes but poor at capturing the kind of qualitative judgement, discretion or good-faith obligations that many commercial contracts rely on.
A smart contract also cannot verify facts about the outside world on its own. If a contract depends on something happening off-chain, such as a ship arriving at port or an invoice being genuinely due, the code needs a data feed, known as an oracle, to tell it. If that oracle is wrong, manipulated or simply unavailable, the smart contract will still execute based on bad information, and there is no legal reason this makes the underlying obligation somehow different. The parties are left with an ordinary contractual dispute about incorrect performance, only the performance already happened automatically before anyone could stop it.
Automatic execution creates a further problem: a smart contract does not pause to ask whether it should still go ahead if circumstances change, if one party wants to rely on a right to terminate, or if a court later grants an injunction. Code that has already executed cannot easily be unwound. Recovering money or assets that have already been transferred by an immutable process usually requires a separate legal claim, such as for restitution or breach of contract, brought through the ordinary courts, not through the smart contract itself.
Smart contracts also do not automatically resolve questions of capacity, consumer protection, unfair contract terms, or statutory formalities. Some transactions, such as certain land dealings or agreements needed in writing and signed under specific statutes, still require particular formalities that pure code cannot satisfy on its own. And a smart contract cannot decide jurisdiction or applicable law for you: if the parties are in different countries and have not addressed this, working out which country’s courts and laws apply can be genuinely difficult, especially where the platform running the code is decentralised and has no obvious home.
Where this leaves businesses using them
The practical approach favoured by lawyers advising on this area is a hybrid one: a natural-language agreement that sets out the parties’ rights, obligations, dispute resolution mechanism and governing law, with the smart contract doing the mechanical work of performance underneath it. That way, if the code and the parties’ actual intentions diverge, or something goes wrong with an oracle or an unforeseen event, there is a legal document a court can interpret rather than only a string of executed transactions.
Anyone building or relying on smart contracts for anything beyond low-value, low-risk transactions should get specific advice on drafting the accompanying legal wrapper, on dispute resolution clauses, and on which jurisdiction’s courts would actually have power to intervene if the code does something the parties did not intend.
Where to check further
The Law Commission’s 2021 report on smart legal contracts is the most authoritative UK analysis of how existing contract law applies to this technology, and the Law Society publishes practical guidance for solicitors advising clients on blockchain-based agreements. Businesses should also check gov.uk for any developments in digital assets and electronic trade documentation law, since this is an area regulators continue to refine.