Wayne State University law professor Peter Henning, a former Justice Department lawyer, commented about a higher court ruling on evidence used in a case involving former Macomb County Prosecutor Carl Marlinga and Warren real estate broker Ralph Roberts. Marlinga and Roberts were implicated in a scheme to swap prosecutorial favors for political contributions. Henning said the admissibility of taped conversations between Marlinga and Roberts are crucial to the charges against Roberts, but that the ruling could be challenged later. \"This will be an issue on appeal if there is a conviction because this is the linchpin of the government\'s case,\" Henning said.