The federal antitrust laws provide both criminal and civil enforcement options.
Antitrust violations are like public nuisances in that private individuals lack standing to sue.
If read literally, Sherman Act section 1 makes almost all contracts a federal felony. It is an antitrust violation for a seller to give, but it is not an antitrust violation for a buyer to request, illegal price discrimination. The federal antitrust laws apply equally to intRAstate commerce and intERstate commerce.