Content Moderation on End-to-End Encrypted Systems: A Legal Analysis
Online messaging platforms like Signal and Google’s Messages increasingly use end-to-end encryption (E2EE), in which messages are encrypted on the sender’s device and decrypted on the recipient’s, so that no one else—not even the platform itself—can read them. Although E2EE protects privacy and advances human rights, the law enforcement community and others have criticized its growing use. In their view, E2EE prevents platforms and government authorities from responding to abuses and criminal activity, including child exploitation, malware, scams, and disinformation. At times, they have argued that E2EE is inherently incompatible with effective content moderation.
Computer science researchers have responded to this challenge with a suite of technologies that enable content moderation on E2EE platforms. These technologies—message franking, forward tracing, homomorphic encryption, and automated client-side scanning— preserve some of the essential privacy guarantees of E2EE while enabling the targets of abuse to detect and report it. These technical advances, however, raise legal questions. If E2EE messages are supposed to be private from a messaging platform, and the platform participates in detecting whether those messages are abusive, is that an “interception” of an “electronic communication” prohibited under the Wiretap Act?
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Charles Duan & James Grimmelmann
Charles Duan, Assistant Professor of Law, American University Washington College of Law; James Grimmelmann, Tessler Family Professor of Digital and Information Law, Cornell Law School and Cornell Tech.