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Kirsten Martin, Helen Nissenbaum & Vitaly Shmatikov
Kirsten Martin, Helen Nissenbaum & Vitaly Shmatikov

University of Notre Dame and Cornell Tech

When (ET)


No Cookies for You: Evaluating the Promises of Big Tech’s “Privacy-Enhancing” Techniques


We examine three common principles underlying a slew of “privacy-enhancing” techniques recently deployed or scheduled for deployment by big tech companies: (1) “We deny (or throttle) access to your data by third parties!”; (2) “We minimize the use and retention of raw data!”; and (3) “Your data never leaves your device!” Our article challenges these principles, not on the grounds that techniques offered to implement them are unsuccessful in achieving their stated goals. Instead, we argue that the principles themselves fall short because their underlying conception of privacy is flawed. Through philosophical analysis and technical scrutiny we reveal the misalignment between principles and a sound conception of privacy. We reinforce our findings, empirically, with a series of factorial vignette user studies, which demonstrate a surprising gap between principles and actual privacy expectations.


Kirsten Martin is the William P. and Hazel B. White Professor of Technology Ethics and is Professor of IT, Analytics, and Operations in the Mendoza College of Business at the University of Notre Dame. She was also the Director of the Notre Dame Technology Ethics Center (ND-TEC) from 2021-2023.

Helen Nissenbaum is the Andrew H. and Ann R. Tisch Professor at Cornell Tech and in the Information Science Department at Cornell University. She is also Director of the Digital Life Initiative, which was launched in 2017 at Cornell Tech to explore societal perspectives surrounding the development and application of digital technology, focusing on ethics, policy, politics, and quality of life.

Vitaly Shmatikov is a Professor of Computer Science at Cornell University and Cornell Tech. Before joining Cornell, he worked at the University of Texas at Austin and SRI International. He received the Caspar Bowden PET Award for Outstanding Research in Privacy Enhancing Technologies three times, in 2008, 2014, and 2018, and was a runner-up in 2013.

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