This chapter provides an in-depth exploration of corpora, beginning with a historical overview of their development and their crucial role in linguistic research. It outlines the evolution of corpora and their significance in studying various aspects of language, with a particular focus on their application to legal discourse. The chapter includes a description of different types of corpora, along with a detailed discussion of key features such as corpus representativeness and methodological considerations, highlighting their relevance in legal linguistic studies. Furthermore, it introduces three diachronic legal corpora specifically selected for this work: the Corpus of Historical English Law Reports (CHELAR), the British Law Reports Corpus (BLaRC) and the Bononia Legal Corpus (BoLC). These corpora will be consulted to carry out a comprehensive linguistic analysis of the evolution of legal English, specifically focusing on elements of legalese and gendered language.