Property rights in a shared-spectrum paradigm define the access rules that limit unavoidable interference (and corresponding capacity degradation) from diverse networks. This degradation, or overhead, could be limited by requiring one standardized PHY/MAC layer, like LTE. However, to serve niche applications or allow new technologies, property rights must allow implementation freedom. But freedom to implement implies freedom to implement strategic misbehavior. So, rights must also be credibly enforceable, which adds another unavoidable overhead. This poster explores the enforcement overhead of a particular scheme: based on a secondary's past behavior, a database issues or withholds temporary tokens for band access. We explore the overhead required to guarantee sharing rules are followed.