A criminal antitrust investigation can be opened as a preliminary inquiry or as a grand jury investigation.

When presented with a request to open a preliminary inquiry, the Antitrust Division considers: (a) whether there is reason to believe that an antitrust violation may have been committed; (b) what amount of commerce is affected; (c) if the investigation will duplicate or interfere with other efforts of the Division, the Federal Trade Commission, a United States Attorney, or a state attorney general; and (d) whether allocating resources to the matter fits within the needs and priorities of the Division. If additional evidence of an antitrust violation is gathered through the preliminary inquiry phase, then a request for grand jury authority can be made.

When presented with a request to open a grand jury investigation, the Antitrust Division considers the prior factors along with whether it is likely that if sufficient evidence confirming the alleged anticompetitive conduct is developed, the Antitrust Division would proceed (or approve proceeding) with a criminal prosecution.

When a significant amount of evidence is available at the inception of a case, a request can be made to seek grand jury authority without going through the preliminary inquiry phase.

[updated April 2022]