The explosion of peer-to-peer file sharing has forced a reexamination of the essential structure of copyright law in the United States. In a digital, interconnected world, the dispersion of copying and distribution activities makes it more difficult for copyright holders to identify users who derive value from their works. And at least theoretically, the inability to capture such value could ultimately jeopardize the incentive to produce and distribute creative expression. There is widespread disagreement over what, if anything, should be done about these threats. While suggestions range from copyright abandonment to digital lockup, two of the principal proposals share an important common feature: each would replace our current law, which c...