
TRUST BUT VERIFY:
A GUIDE TO ALGORITHMS AND THE LAW
Deven R. Desai* and Joshua A. Kroll**
TABLE OF CONTENTS
I. INTRODUCTION .................................................................................. 2
II. ALGORITHMS: THE CONCERNS ........................................................ 6
A. Transparency and Accountability: Two Complementary
Views .......................................................................................... 7
B. Algorithms, Public Sector Concerns .......................................... 12
C. Algorithms, Private Sector Concerns ........................................ 16
III. ALGORITHMS: A PRIMER .............................................................. 23
IV. TO HALT OR NOT TO HALT .......................................................... 29
A. Undecidability and the Halting Problem ................................... 30
B. The Halting Problem Applied to Algorithmic
Transparency ........................................................................... 32
V. PRACTICAL SOLUTIONS FROM COMPUTER SCIENCE ...................... 35
A. Testing and Evaluating Algorithms ............................................ 36
1. White-Box Testing .................................................................. 37
2. Black-Box Testing .................................................................. 38
3. A Third Way: Ex-Post Analysis and Oversight ...................... 39
B. Dynamic Systems and the Limits of Ex-Post Testing ................. 41
VI. A TAXONOMY OF POTENTIAL SOLUTIONS ................................... 42
A. Public Systems ............................................................................ 43
B. Private Systems .......................................................................... 45
1. Explicitly Regulated Industries ............................................... 46
2. Building Trust: Implicitly Regulated Industries or
Activities ........................................................................... 48
3. The Challenge of Dynamic Systems ....................................... 49
* Associate Professor of Law and Ethics, Georgia Institute of Technology, Scheller College
of Business; J.D., Yale Law School; Affiliated Fellow, Yale Law Information Society Project;
former Academic Research Counsel, Google, Inc. I, and this Article, have benefitted from dis-
cussions with and input from Solon Barocas, Ariel Feldman, Brett Frischmann, Andrew Selbst,
and Peter Swire, and from attendees at Privacy Law Scholars Conference, 2016 at George
Washington University Law and at the Law and Ethics of Big Data Colloquium at University of
Indiana, Bloomington, Kelley School of Business. I thank Jason Hyatt for excellent research
assistance. This Article was supported in part by summer research funding from the Scheller
College of Business and an unrestricted gift to the Georgia Tech Research Institute by Google,
Inc. The views expressed herein are those of the author alone and do n ot necessarily reflect the
view of those who helped with and supported this work.
** Postdoctoral Research Scholar, UC Berkeley School of Information.