 "To dispose of this case on the ground suggested would entail both overruling a leading decision of this Court and brushing aside the possibility that we would be creating more problems than we would supposedly be solving," he said in conclusion.Frankfurter's concurring opinion, in which he was joined by Justices William O. Douglas, John Marshall Harlan II and newly appointed William Brennan, argued nonetheless for Roberts' objective test of locating entrapment in the manner in which the government agents carried out their investigation.