A Chicago Sun-Times reporter must testify at R. Kelly's child pornography trial.

Judge Vincent Gaughan made that ruling Friday.

The defense wants to call Jim DeRogatis to ask how he got a sex tape in 2002 that's now the center of the trial.

The judge rejected arguments from a lawyer for the Sun-Times that DeRogatis' actions should be privileged under the First Amendment.

The singer has pleaded not guilty to child pornography charges.

The trial resumes Monday.