This material is based upon work supported by the National Science Foundation under Grant No. CNS-0524745. Special thanks to my legal supervisor, Deirdre K. Mulligan, and my PhD adviser, Pam Samuelson. Discussions with the following people were important in the development of this work: Eddan Katz, Ka-Ping Yee, David Molnar, veen Satry, Dan Wallach, Michael Shamos and Mitch Kapor.