Over the past ten years, the debate over “network neutrality” has remained one of the central debates in Internet policy. Governments all over the world have been investigating whether legislative or regulatory action is needed to limit the ability of providers of Internet access service to interfere with the applications, content, and services on their networks.

In addition to rules that forbid network providers from blocking applications, content, and services, rules that forbid discrimination are a key component of any network neutrality regime. Nondiscrimination rules apply to any form of differential treatment that falls short of blocking. Policymakers who consider adopting network neutrality rules need to decide which, if any, forms of differential treatment should be banned.

This Article makes five contributions: First, it proposes a substantive framework that policymakers can use to evaluate alternative proposals for network neutrality rules and assess specific forms of discriminatory conduct. Second, the Article evaluates eight existing proposals for nondiscrimination rules and the Open Internet Order’s nondiscrimination rule against this framework and proposes a nondiscrimination rule—ban application-specific discrimination, allow application-agnostic discrimination—that policymakers should adopt around the world—a rule that the FCC’s Open Internet Order adopted in part. Third, the Article highlights the differences between an antitrust framework and the broader theoretical framework on which most calls for network neutrality regulation are based and explains why an antitrust framework does not capture all instances of blocking or discrimination that concern network neutrality proponents. Fourth, the Article offers the first in-depth analysis of the relationship between network neutrality and new network-level services called Quality of Service. Finally, the Article provides the first detailed analysis of the Open Internet Order’s nondiscrimination rule for fixed broadband Internet access.