The Justice Department is investigating whether five television networks violated antitrust law when they briefly stopped providing pool coverage of President Donald Trump, a department spokesperson said.

The inquiry covers the networks that make up the White House television pool, which rotates responsibility for recording the president’s public appearances and travel and sharing that material with other outlets. A department official said civil investigative demands were sent Friday.

The pause followed Trump’s decision to bar three news organizations from White House grounds. Other pool networks briefly declined assignments after one of those organizations was removed from the rotation. The three challenged the ban in court, arguing that it violated the First Amendment. Their access was restored about a week later after a judge ruled that the administration had to restore it temporarily.

Justice Department spokeswoman Emily Covington said investigators are examining whether the networks’ collective action violated antitrust law. The inquiry has not established a violation.