»Claim, Infringement and Presentness. An Investigation Starting from the Functional Contexts of our Legal System to the Individual Questions of the Nature of Claims in rem.«: The thesis deals with the roots of the concept of the claim in the law of the 19. century and its present-day contour. It comes to the conclusion that the claim is a pure instrument of legal realization and that it must be separated from the respective substantive right, which assignes value. The present violation of a substantive right is a prerequisite of any claim. Finally, the thesis examines the conclusions that can be drawn from this for in rem claims, especially §§ 985 and 1004 BGB.