ENThe Polish-Lithuanian Commonwealth was a multicultural state in which Latin, Orthodox, Armenian and Jewish cultures crossed and mixed together. There were also Muslim elements in this mosaic resulting from the presence of a group of Tatars in the Grand Duchy of Lithuania and - from the second half of the seventeenth century - also in the Kingdom of Poland. Their population is estimated to have reached about 10,000 people - that is, less than 1 per cent of the population of the Grand Duchy of Lithuania. Nonetheless, their ethnic, cultural and religious distinctiveness makes this group of Tatars an interesting subject of research. This goes also for their legal culture. The aim of this article is to point out some aspects of change in Tatar legal culture on the basis of published fragments of court books containing acts of the Lithuanian Tatars from the sixteenth to the eighteenth century.