Where competitors agree to a horizontal anticompetitive behavior, whether that constitutes a per se violation of the Illinois Antitrust Act subsection 3(1) depends on the nature of the restraint, not on whether it was facilitated by a vertical noncompetitor.The 1st District Appellate Court answered two certified questions from Cook County Circuit Judge Raymond W. Mitchell.Colony Display LLC (Colony) designs, manufactures, and installs fixtures, exhibits, and displays for a number of different types of business. The …