Modified Final Judgment

The Modified Final Judgment (MFJ) was the 1982 consent decree between the United States Department of Justice and AT&T that mandated the breakup of the Bell System, implemented in 1984. The MFJ separated AT&T's long-distance operations from its local service monopolies, creating seven Regional Bell Operating Companies and imposing line-of-business restrictions to prevent re-integration.

The MFJ is the most celebrated structural remedy in American antitrust history, yet its long-term effectiveness is deeply contested. Within two decades, the Telecommunications Act of 1996 had dismantled the separation requirements, and the Baby Bells had merged back into a concentrated oligopoly. The MFJ's fate suggests that structural separation without ongoing regulatory architecture is a temporary pause in the natural concentration of network-effect markets.