On Tuesday, the Reporters Committee for Freedom of the Press and 18 other media organizations filed a brief in support of reporter Jamie Kalven’s motion to quash a subpoena.  Kalven is being subpoenaed to testify in the trial of Chicago Police Officer Jason Van Dyke, who was charged with murder in the 2014 shooting death of 17-year-old Laquan McDonald.

“The public interest in protecting confidential sources is particularly compelling in this case,” the media coalition wrote in the brief. “Kalven’s reporting exposed misconduct by the Chicago Police Department and an official cover-up that led to a public accounting and an investigation by the U.S. Department of Justice.”

In the brief, the coalition argues that the Illinois Reporter’s Privilege Act protects Kalven from being forced to testify.

“This story is a perfect example of why reporters must be able to protect confidential sources,” said Bruce Brown, executive director of the Reporters Committee for Freedom of the Press. “Without the sources in this case, the public may never have known how McDonald died, or how the Chicago Police Department investigated the shooting, information that is necessary for the public to hold government and law enforcement accountable.”

The officer charged in the case has opposed Kalven’s motion to quash the subpoena, but his reasons for doing so are secret.

“Amici do not have access to Van Dyke’s opposition papers containing his legal argument as to why the reporter’s privilege has been overcome in this case,” the coalition wrote in the brief. “Despite the public’s presumptive right of access to court records under the First Amendment, common law, and Illinois statutory law, Van Dyke’s opposition papers have been filed under seal. Amici and the public are thus left in the dark in a case of great public importance.” Read the full brief here.