The [DOJ Office of Professional Responsibility] that polices [DOJ] lawyers' conduct has been operating under a growing shroud of secrecy. It is taking on some of the weightiest issues in government -- examining the role Justice's lawyers played in formulating administration interrogation policies for suspected terrorists and in endorsing a National Security Agency program of warrantless electronic surveillance. It has ... the task of deciding whether department lawyers engaged in selective prosecution of Democratic political figures. It also is looking into lawyers' involvement in a decision ... to deport a Canadian citizen to Syria, where he was imprisoned and tortured. But officials have declined to say whether even one government lawyer has been found to have engaged in professional misconduct in connection with the war on terrorism -- despite often fierce criticism from civil liberties groups, defense lawyers and judges. The [unit] has exonerated department lawyers in at least two high-profile terrorism-related investigations. The office found that department lawyers had not engaged in misconduct in connection with ... using special warrants to round up and incarcerate men after Sept. 11. The OPR also exonerated department lawyers in ... the case of Brandon Mayfield, a Muslim attorney in Portland, Ore., who was detained when the FBI erroneously linked his fingerprints to ... the March 2004 Madrid train bombings. But the resolution of most matters investigated by the OPR remains closely guarded, even in cases where courts have found evidence of serious prosecutorial misconduct.