The Justice Department has opened an antitrust investigation into ABC, CBS, CNN, NBC and Fox News, questioning whether the networks violated competition law by declining to fill CNN’s White House press-pool shifts when the administration barred the network from participating. The department said Saturday it is examining whether the networks’ coordination amounted to an illegal group boycott under the Sherman Act. The networks had agreed not to substitute for CNN on days when the administration prevented it from taking its turn in the pool, though decisions were made day by day. The five networks did not comment on the investigation. The White House television pool shares the work and cost of covering presidential events in places with limited space, including aboard Air Force One. After CNN was blocked from a planned shift, the networks did not cover an event involving President Donald Trump and Chinese President Xi Jinping. The probe unfolds amid a wider dispute over press access. Last month, Trump’s aides barred CNN, Politico and MS NOW from the White House after the president criticized their coverage. The administration also revoked the press passes of more than 70 journalists. The three outlets sued to restore access, while the Justice Department has defended the restrictions in court on national security grounds. A federal judge temporarily ordered the press passes restored and was expected to issue a longer-term decision by Tuesday evening. Press-freedom advocates condemned the antitrust inquiry. Bruce Brown, president of the Reporters Committee for Freedom of the Press, called it an attempt to intimidate journalists, adding that it came on top of the White House’s other retaliatory actions. Cornell law professor Michael Dorfman said the investigation could still face scrutiny over whether the networks’ conduct was reasonable, regardless of any political motivation behind it. He questioned why cooperation to protect press access would be treated differently from the pool’s routine coordination, which is necessary because venues have limited space. The dispute is part of a broader pattern of conflict between the administration and news organizations. ABC and its parent company, Disney, are separately suing over a federal broadcast regulator’s review of the licenses for the company’s eight local television stations. Trump has also called for ABC and NBC to lose their broadcast licenses, and has filed personal lawsuits against several major news organizations.