The aim of this thesis is to shed light on language variation and language change in judicial protocols from the municipal court in Stockholm during the period 1476−1626. These documents provide a unique insight into late medieval and early modern use of written vernacular. The main material consists of 700 courtroom notes from seven different periods of time, a hundred documents from each year: 1476, 1499, 1525, 1550, 1575, 1600, and 1626. The study draws theoretically on functional linguistics; more specifically, it utilizes Halliday’s systemic-functional grammar, Ulf Teleman’s (1985) theoretical model of language change, as well as dialogism. The results are presented in four analytical chapters. In the first of these, the aim is to systemize the somewhat heterogeneous material, and the corpus is divided in two different ways: one due to judicial content (‘categories of matter’), and one due to textual structure (‘discourse levels’). These systemizations also serve as a methodological foundation for the lexicogrammatical analysis in the following chapters. A main result is that multi-party cases over time develop a functional need for new communication strategies, while unilateral cases already from the beginning seem to bear a more deep-rooted textual stability. In addition, there is a significant increase of discourse level 3, representing communicative events outside the courtroom, in multi-party cases found in texts from 1600 and 1626. In the two following chapters, lexicogrammatical resources of ‘personal reference’ and ‘time and tense’ are analysed. The texts realize different patterns of anaphora, where individuation explains much of the variation: texts with high degree of individuation (criminal cases) materialize a high degree of pronouns, whereas texts regarding property issues materialize low individuation with few pronouns and many full NPs. Regarding the use of tense, the past tense is the most common tense. Still, the study shows an diachronic increase in the use of present tense. The last analytical chapter examines the use of three lexical features: judicial pronouns; word pairs; and nominalizations. The results show that judicial pronouns and word pairs typically occur in registrations matters; nominalizations occur throughout the genre. In the last chapter, the results and implications of the thesis are summated and discussed. The results point towards a pragmatic use of the written language. Although the lexicogrammatical resources are the same during the period, the usages vary. Hence, linguistic variation and change are highly motivated by an intercommunion of contextual factors such as a more solid administrative literacy, a changing litigation, and an increase of legal demands for linguistic precision and documentation. It is argued that the language variety in the genre can be understood as instantiations of different registers.