State attorneys general can play an important role in antitrust enforcement on matters of particular concern to local businesses or consumers. They may bring federal antitrust suits on behalf of individuals residing within their states (“parens patriae” suits), or on behalf of the state as a purchaser. The state attorney general also may bring an action to enforce the state’s own antitrust laws. In merger investigations, a state attorney general may cooperate with federal authorities. For more information on joint federal-state investigations, consult the Protocol for Coordination in Merger Investigations.