This chapter examines the relationship betweenprivate ordering/self-regulation and national contract law rules. It assesses the impact that private ordering exerts upon national contract law, with particular reference to the legal response to the ISDA Master Agreement. The chapter also examines aspects of market-specific regulation in the United Kingdom. Many areas traditionally covered by common law rules, such as the control of unfair terms in contract, are now the preserve of regulators such as the Financial Conduct Authority (FCA) and the Competition and Markets Authority. In addition to the activities of regulators, enforcement of consumer contract law can be undertaken by a range of organisations and dispute resolution services provided by private entities or through various ADR schemes. There are often significant divergences between the regulatory approach to contract enforcement and the applicable contract law rules on the issue. To illustrate this, the FCA review of the mis-selling of interest rate hedging products to ‘unsophisticated’ customers is contrasted with case law on misrepresentation covering the corresponding scenario under the common law.