Northwestern's legal clinic filed a petition seeking a new trial for McKinney after students interviewed witnesses who said they fingered McKinney only after being beaten by police. But prosecutors parried with a subpoena for Protess' records and claim students' paid two witnesses to prove their case.

"It goes to the interest and the bias of the students," Sally Daly, a spokesperson for the Cook County State's Attorney Office, told local media. "Did they receive a better grade in the class? Was there incentive for these students to develop additional information (about McKinney's innocence)?"

Though the students' have not been subpoenaed individually, the case has provoked a furor among journalists. News organizations including the New York Times and The Washington Post have filed briefs arguing that student journalists have the same legal protections as working journalists.

And one former judge has gone on record criticizing prosecutors for their "relentless attempt to discredit" the Medill Innocence Project.

Judge H. Lee Sarokin, who served 17 years on the federal bench, called prosecutors' allegations "ironic."

"The police pay informants everyday for information,'' Sarokin wrote at The Huffington Post. "Prosecutors offer criminals (not just witnesses) plea deals with reduced sentences everyday for cooperation and testimony in support of charges against others. Should the prosecutors' personal records be examined by the defense in order to determine what their motives were in making these deals?"

Northwestern's attorneys are expected to argue today before Cook County Circuit Judge Diane Cannon that the subpoena should be thrown out.