This chapter explores the ‘gap’ between legal rules and their implementation. Legal rules may appear to require, allow or proscribe certain activities. But the invocation or enforcement of the rules may reshape them into a form that bears little resemblance to the ‘law in books’. The chapter provides examples of how the various research methods have been used by socio-legal researchers in different contexts. It demonstrates that legal decisions cannot be understood solely by reference to the content of statutes and precedents. W. G. Carson’s argument regarding the conventionalisation and ambiguity of factory crime, may apply specifically to the attitudes of factory inspectors or it may apply to community attitudes more generally. The chapter looks at the transformative effects that impending litigation may have upon a civil dispute or a criminal case. Most of the socio-legal research in this area has focused on criminal cases, but some of the conclusions are equally applicable to civil cases.