The law of theft emerged in an age in which most wealth was found in tangible objects, such as money, domesticated animals, crops, and furnishings. Today, our economy is increasingly based on things that are intangible, including information, ideas, identities, and intellectual property. For the last decade or so, the music and movie industries, along with law enforcement authorities and various legislatures, have insisted that the law of theft, and the stigma it conveys, should apply, essentially intact, to the misappropriation of intangibles, such as that which occurs when content is illegally downloaded from the Internet.

This presentation will consider this claim of theft equivalence, arguing that for some good or service to count as property for purposes of theft, it must meet two necessary and sufficient conditions: first, it must be commodifiable, meaning that it is capable of being bought and sold; and, second, it must be rivalrous, meaning that consumption of it by one consumer will prevent simultaneous consumption by others. This conceptual framework will then be applied to a number of problematic forms of putative property, including credit taken by the plagiarist, information, identities, trade secrets, copyrights, patents, trademarks, and so-called virtual property.