The power and influence of dominant tech platforms — Google, Facebook, and Amazon, in particular — have become a central topic of debate. In this paper, I argue that these firms are best understood as the core infrastructure of our 21st century economy and public sphere. Whether it is Google's search, Facebook's newsfeed, or Amazon's retail and logistics system, these firms are increasingly integral to economic and social activity. Viewing these firms as “infrastructure” helps to better diagnose the nature of the problems posed by these Internet platforms. Doing so also, in turn, offers some novel legal and policy responses. This paper proceeds in three main parts. First, it develops this infrastructural diagnosis of the problem with Internet platforms. While much of the current debate has revolved around issues like “fake news,” and disparities of bargaining power between, for example, Amazon and publishers, the paper suggests that these clashes are actually symptomatic of a deeper problem, that these firms are effectively privately-run infrastructure. This diagnosis helps define more sharply the central legal and policy challenge posed by these firms: if the platforms themselves are effectively governors of much of our informational, economic, and political life, how then should our public policy govern these governors? The paper develops this infrastructural view of platforms by recovering and adapting an old tradition of legal thought and regulatory strategy, stemming from the “public utility tradition.” Second, the paper adapts these public utility concepts to map the precise nature of informational infrastructural power. Specifically, I identify three types of infrastructural power exercised by these Internet platforms: transmission power, gatekeeping power, and scoring power. These types of power are subtle and often hidden from view, and explain how Internet and informational platforms can often appear diffuse, decentralized, and thus unproblematic, while at the same time exercising outsized economic power. Third, the paper explores how public utility regulatory theory might be adapted to address these distinctive types of infrastructural power
