In the course of the sixteenth century, in the Low Countries maritime law was changing. At first, damages caused during maritime transport (“averages”) were compensated on the basis of customs of limited scope and calculation, starting from “facts and figures”. From the 1550s onwards, legal scholars developed new views; they revised norms, some of which came from below, while others were imposed by the sovereign. Both in legislation and in jurisprudential commentaries, the Roman rules of general average were revived. The legal authors made use of a more principled, humanistic method of interpretation. Their views did not contradict mercantile opinions; instead, merchants called for necessary adjustments of the law. The changes in doctrine and legislation responded to developments in the organization of the maritime industry. Although the legal scholars could have doubts about the older rules and how to reconcile them with a principled approach, their contribution to updating the rules was crucial.