The article analyzes the problem of understanding codification processes by the doctrine of law in the Baltic provinces of the Russian Empire. Taking into account the significance of the German legal thought for the legal doctrine of Baltic provinces, the views of German jurists are also examined. It is established that characteristic features of codification in German jurisprudence had already been formulated in a manner analogous to the present ones in the 19th century. In the 19th century, similar to modern times, codification seemed to be a comprehensive process both formally and substantively updated by means of legislative acts. No other sources of law, including customary law, should have acted along with codification. As a consequence, uncertainty of a common legal tradition was eliminated and comprehensive understandability was achieved. At the same time, it is recognized that representatives of the Baltic legal thought, despite German influence, understood the processes of codification on the basis of their own ideas that often were not at all correlated with the German doctrine, but were more in line with the general imperial Russian view of those phenomena. It is argued that the processes of systematization and codification of the Baltic law had encouraged the further development of legal thought both in the entire Russian Empire and in the Baltics. The situation examined in the study, in authors' opinion, shows only one thing. Law in the 19th century was formed not by practitioners or jurists (scholars), but by the law-maker (or the bodies prescribed and authorized by the law-maker). The Baltic law codification entailed changes for various sources of Baltic law that had operated so far. Meanwhile, those processes characterized not only the Baltic region, but were seen throughout Europe. Codification becomes the main, if not the only, source of law. Thus, the need for a common doctrine combining the sources of law and common law was lost.