While ‘code is law’ according to smart contract inventors, the nature of the relationship between legal contracts and smart contracts is complex. This chapter explores that relationship, and the issues that affect it. After a brief introduction, the second section is dedicated to fundamentals, presenting the basic concepts and explaining the temporal relationship between a legal contract and a smart contract. The third section entails two sub-sections. The first sub-section, dedicated to situations where a smart contract is preceded by a legal contract, deals with issues relating to interpretation, performance or gap-filling of the contract. The second sub-section focuses on situations where a smart contract pre-exists a legal contract by exploring the conclusion mechanism, the existence and the validity of the contract. The fourth and last section offers a conclusion summarizing the findings of the chapter.