Sociology as one of the social sciences is an empirical science and its research is based on facts. Sociologists use the concept of social facts, meaning ways of proceeding that can be distinguished from among various behaviours common in society. However, these are phenomena whose features clearly differ from phenomena studied by other sciences. In this work, the author wanted to take a closer look at the influence of the sociology of law on the broadly understood constitutional law, because in recent years the literature has not paid much attention to this issue. In this work, the author, based on the definition of constitutional law in the broad sense, and thus not limited only to the analysis of the codified constitutions, will try to indicate the important role of sociology and its research methods in the dogmatic study of this area of law. In the first place, the work will discuss examples showing the important role of sociology of law in establishing new and interpreting the existing law – on the example of religious law, the law of local self-government, the states of emergency law. This discussion will be supported by references to examples of legislation from various countries and by referring to the opinions of various legal theorists. Then the author will move on to an even broader approach to constitutional law, as the perspectives of international constitutionalism, i.e., acts of international law, including those recognized by some as international constitutions and their sociological and legal analysis. The considerations presented in the paper are aimed at showing the important role of sociological sciences in the contemporary science of constitutional law.