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57 UCLA L. Rev. 1701 (2009-2010)
Broken Promises of Privacy: Responding to the Surprising Failure of Anonymization

handle is hein.journals/uclalr57 and id is 1713 raw text is: BROKEN PROMISES OF PRIVACY: RESPONDING
TO THE SURPRISING FAILURE OF ANONYMIZATION
Paul Ohm
Computer scientists have recently undermined our faith in the privacy-
protecting power of anonymization, the name for techniques that protect the
privacy of individuals in large databases by deleting information like names and
social security numbers. These scientists have demonstrated that they can often
reidentify or deanonymize individuals hidden in anonymized data with
astonishing ease. By understanding this research, we realize we have made a
mistake, labored beneath a fundamental misunderstanding, which has assured us
much less privacy than we have assumed. This mistake pervades nearly every
information privacy law, regulation, and debate, yet regulators and legal scholars
have paid it scant attention. We must respond to the surprising failure of
anonymization, and this Article provides the tools to do so.
IN TRO DU CTIO N  ................................................................................................................. 1703
I.  ANONYMIZATION     AND  REIDENTIFICATION  .............................................................. 1706
A .  The  Past: Robust Anonym ization  .................................................................... 1706
1.  U biquitous A nonym ization  ....................................................................... 1707
a.  The Anonymization/Reidentification Model ................................... 1707
*    Associate Professor, University of Colorado Law School. This Article was presented at the
Privacy Law Scholars Conference and at conferences and faculty workshops at Harvard's Center for
Research and Computer Science and Berkman Center, Princeton's Center for Information Technology
Policy, Fordham University Center for Law and Information Policy, University of Washington School
of Law, University of Washington's Computer Science & Engineering Department, NYU Information
Law Institute, DePaul Center for IP Law and Information Technology, International Association of
Privacy Professionals Global Privacy Summit, and the University of Colorado Law School. I thank
all participants for their comments.
Thanks in particular to Caspar Bowden, Ramon Caceres, Ryan Calo, Deborah Cantrell, Danielle
Citron, Nestor Davidson, Pierre de Vries, Vasant Dhar, Cynthia Dwork, Jed Ela, Ed Felten, Victor
Fleischer, Susan Freiwald, Brett Frischmann, Michael Froomkin, Simson Garfinkel, Lauren Gelman, Eric
Goldman, James Grimmelmann, Mike Hintze, Chris Hoofnagle, Clare Huntington, Jeff Jonas, Jerry
Kang, Nancy Kim, Jon Kleinberg, Sarah Krakoff, Tim Lee, William McGeveran, Deven McGraw, Viva
Moffat, Tyler Moore, Arvind Narayanan, Helen Nissenbaum, Scott Peppett, Jules Polonetsky, Foster
Provost, Joel Reidenberg, Ira Rubinstein, Andrew Schwartz, Ari Schwartz, Vitaly Shmatikov, Chris
Soghoian, Dan Solove, Latanya Sweeney, Peter Swire, Salil Vadhan, Michael Waggoner, Phil
Weiser, Rebecca Wright, Felix Wu, and Michael Zimmer for their comments. This research was
supported by a pre-tenure research leave grant by the University of Colorado Law School, and for this I
thank Dean David Getches and Associate Dean Dayna Matthew. Finally, I thank my research assistant,
Jerry Green.

1701

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