Over the course of the last decade, in response to significant pressure from the US government and other governments, service providers have assumed private obligations to regulate online content that have no basis in public law. For US tech companies, a robust regime of "voluntary agreements" to resolve content-related disputes has grown up on the margins of the Digital Millennium Copyright Act (DMCA) and the Communications Decency Act (CDA). For the most part, this regime has been built for the benefit of intellectual property rightholders attempting to control online piracy and counterfeiting beyond the territorial limits of the United States and without recourse to judicial process.

The reach of privately ordered online content regulation is wide and deepening. It is wide in terms of the range of service providers that have already partnered with corporations and trade associations to block sites, terminate accounts, and remove content without court orders. That range now includes payment processors and digital advertising networks in addition to Internet access providers, search engines, and social media platforms. It is deepening with reference to the Internet's protocol stack, migrating downward from the application layer into the network's technical infrastructure, specifically, the Domain Name System (DNS). While enforcement of intellectual property rights is the purpose for which these agreements exist, the site-blocking procedures they institutionalize are readily adaptable for use in censoring all kinds of disfavored content.

Recent private agreements between DNS intermediaries and intellectual property rightholders cross the Rubicon. Such agreements, which are the subject of a draft book chapter I recently posted to SSRN, should be cause for special concern among open Internet advocates, because they transform technical network intermediaries into content regulators in an unprecedented way. They expand the remit of domain name registrars and registry operators beyond their raison d'être, which is the administration of the Internet's addressing system and the maintenance of its operational security and stability. As these private, under-the-radar agreements multiply, they are taking a tangible but hard-to-measure toll on the global environment for freedom of speech and access to information online.