Abstract
Economists have called for the patent system to preclude the grant of overlapping patent rights. However, the literature is silent on what constitutes an overlap of patent rights and on whether any overlap is legally permissible. This article identifies the existence, and determines the validity and consequences, of overlapping patent rights. It finds that there are various types of overlap, and that each type is legally permissible subject to certain conditions. The authors conclude that where overlap is permitted, it should not be considered problematic.