In The Idea of Property in Law, Penner considers the concept of property and its place in the legal environment. Penner proposes that the idea of property as a "bundle of rights" - the right to possess, the right to use, the right to destroy etc. - is deficient as a concept, failing to effectively characterise any particular sort of legal relation, and evading attempts to decide which rights are critical to the "bundle".

Through a thorough exploration of property rules, property rights, and the interests which property serves and protects, Penner develops an alternative interpretation and goes on to consider how property interacts with the broader legal system.