With this article -which is the first of three about the german juridical culture during the first world war- we intend to understand if the german international law thinking can be attributed to the causes of the first world war, and if so, to what extent it encouraged decisions contrary to humanitarian law in force at that time. It is interesting to note how international german scholars seem to be divided: on one side sit those who firmly denied that Germany had violated Belgium and Luxembourg sovereignty and acted violently on their populations, so that they resigned from the Institut de droit International; on the other side sit those who were talking and inspired by pacifism.