Are there regimes of antitrust enforcement? An empirical analysis

In this paper, the authors propose a new index of antitrust enforcement. The index is compiled from quarterly data from the Department of Justice from 1890 to 1989 and is designed to reflect the relative influence of variables that have deterrent effects. The authors use Hamilton's (1989, 1990) regime-switching technique to estimate a model in which the enforcement index follows a regime-specific AR(1) process. The authors find evidence of long-lived regimes. The high enforcement regime, which lasted from about 1910 to the mid-1960s, produced enforcement that was, on average, almost twice as high as the low enforcement regime. In particular, the Reagan years were not a time of transition to low antitrust enforcement, as is commonly claimed. Rather, the transition to a low enforcement regime had taken place some 15 years earlier.