The Justice Department says it is investigating whether five television networks may have violated antitrust law after they briefly declined to provide pool coverage of President Donald Trump.

The networks share a rotating assignment to record the president’s public appearances and travel for other outlets. A department official said civil investigative demands went out Friday. Department spokeswoman Emily Covington said investigators are examining whether the networks’ actions violated antitrust law; the inquiry does not establish a violation.

The pause followed Trump’s decision to bar three news organizations from White House grounds. Other networks briefly declined pool duties after one of those organizations was removed from the rotation. The three sued, arguing the ban violated the First Amendment, and returned about a week later under a judge’s temporary order.

One of the networks under investigation said it had not received a notice from the department but expected one.